Printing Devices Research Articles

Incipient flow properties of two-component fine powder systems and their relationships with bulk density and particle contacts

The effect of incipient flow properties, such as cohesion and internal angle of friction, on the flowability of two-component fine powder systems is of great importance for controlling the process efficiency and quality of industrial products such as developers for electrophotographic (EP) printing devices. In this paper, we have studied the flow properties of model fine powders composed of glass ballotini (d50=69.4μm) and resin toners (d50=6–8μm), using different mixing ratios of the components under a low normal consolidation stress (2kPa) using a ring shear tester (RST). We have found that the dependence of the cohesion of the two-component mixtures on the mixing ratio can be reproduced by a linear superposition of the cohesions of each component weighted by the number of the three different types of interparticle contacts, which suggests that the bulk cohesive properties of fine powder mixtures are dominated by cohesion between particles and the number of each type of particle contacts in the system. Also, the frictional properties of the two-component mixtures are strongly related to the packing density of the mixture, and its dependence on the mixing ratio can be related to the densities of each type of particle contacts. Our results suggest that the dependence of the incipient flow properties of two-component fine powders on the ratio of the components can be predicted by measuring only the flow properties of each component and estimating the ease with which the mixture can be compacted.

Life Cycle Assessment in the Print Industry

SummaryThis article compares life cycle assessment studies performed on imaging equipment for the consumer market in order to identify common practices, limitations, areas for improvement, and opportunities for standardization. The analysis suggests that comparisons across studies are significantly hampered by variability in scope, transparency, data sources, and assumptions; it identifies sources of discrepancy and variability. Of particular concern to printing devices was the definition of a functional unit, which can vary significantly depending on the capabilities and use patterns of a printer. Standardization of the functional unit and related assumptions has a high potential to increase quantitative comparability across studies. At the same time, standardizing the functional unit by paper usage excludes the possibility of comparison to alternative communication media.

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

Inkjet System for Printing Mechanical Reinforcing Patterns Directly on Fragile Membranes Floating on Liquid Surfaces

Ultrathin porous membranes can be employed for applications in the field of micro- and ultrafiltration and offer a low flow resistance. However, due to their thickness below 1 μm they are very fragile. Therefore, we recently reported on a process to increase the mechanical stability by inkjet printing of UV curable inks to create reinforcing patterns on top of these membranes [1]. Based on this laboratory approach we realized now a specific inkjet printing system to apply the process efficiently on larger areas.The membranes are first manufactured on a water surface in a Langmuir trough [2]. Therefore, the inkjet system realized here is composed of a 3D motion system for a multi-nozzle printhead and a UVLED-lamp. In order to prevent waves leading to undefined displacements of the floating membranes the filled trough is stationary while the printhead and the UVLED-lamp are moved. The positioning stages have a high accuracy and enable a precise movement of the printing and UV curing device relative to the membranes. Deviating from previous procedures that needed intermittent support of the porous membrane by a solid support, the reinforcing patterns now are created directly on top of the floating membranes. Deposition is done by multiple motion procedures combined with triggered printing and UV curing events. The patterns can be deposited in several minutes with resolutions of up to 800 dpi covering an area of about 130 cm2. While the porous membranes before application of reinforcement pattern are very fragile, the reinforced porous membranes are stable enough to be lifted off the water surface and handled manually without special precautions.

Palm Oil-Based Bio-Resin for Toner

Recently, research on innovative approach that enables sustainable printing for the well-being of the environment has garnered a lot of attention and development, including non-impact printing industry. Energy conservation and sustainable printing have prompted the industry to explore new technologies or materials for the printing devices and its consumables. This paper will focus on the bio-based toner resin which derived from palm oil-based derivative and the preparation of bio-based toner for electrophotographic printing. Two different alkyd polyester macromers derived from palm oil were used to co-polymerize with petroleum-based monomers to produce the hybrid bio-resins, with bio-based content up to 21% or more. Bio-toners were formulated using these resins followed by evaluation of the printing results from a laser printer. The properties analysis of the bio-resins showed promising and desirable results in comparison to the commercially available, petroleum-based toner resin. The printing quality and performance of the bio-toners did achieve the overall targeted specifications. The outcome of this study has proven that this unique proprietary technology was feasible for toner resin making, in terms of processes, cost advantage, the significance of bio-content incorporated and the printing performance of the biotoner.

Single-pass Inkjet Digital Printing Technology for Commercial Printing Markets

Single-pass inkjet digital printing devices can have over 100,000 nozzles per system for a 4-color B2 format size. Ultimately, an inkjet printing system's success relies on stable and reliable printheads, inks and marking process to produce crisp round dots, and image processing techniques to compensate for process artifacts such as “dot migration or interference” which can cause undesirable streaks and other image defects.At drupa 2012 held in May, several inkjet technologies were introduced and will be reviewed by features and potential.

Fine and ultrafine particles emitted from laser printers as indoor air contaminants in German offices

Various publications indicate that the operation of laser printers and photocopiers may be associated with health effects due to the release of gaseous components and fine and ultrafine particles (UFP). However, only sparse studies are available that evaluate the possible exposure of office workers to printer emissions under real conditions. Therefore, the aim of our study was to assess the exposure of office workers to particulate matter released from laser printers and photocopiers. Concentrations of fine particles and UFP were measured before, during, and after the operation of laser printing devices in 63 office rooms throughout Germany. Additionally, the particles were characterized by electron microscopy and energy-dispersive X-ray spectroscopy. A significant increase of fine particles and UFP was identified in ambient workplace air during and after the printing processes. Particle fractions between 0.23 and 20μm emitted by the office machines significantly affect particle mass concentrations while printing 500 pages, i.e., during the printing process, PM(0.23-20), PM(2.5), and PM(10) concentrations increased in 43 out of the evaluated 62 office rooms investigated. Additionally, a significant increase was observed in submicrometer particles, with median particle number concentrations of 6,503 particles/cm(3) before and 18,060 particles/cm(3) during the printing process. Our data indicate that laser printers and photocopiers could be a relevant source of fine particles and particularly UFP in office rooms.

Enhancing the Specular Effect of Metallic Color Prints by Reducing the Use of Yellow Ink

The MetallicArt technique is used as a visual security feature to hide patterns in CMY images using an additional silver ink. The patterns are hidden under nonspecular viewing conditions and visible under specular viewing conditions. By varying the amount of silver ink, the authors control the intensity of the specular reflection of the printed pattern. Using a spectral reflection prediction model, they can constrain the maximization of the silver ink (S) in order to keep the color difference between the original CMY color and the fitted CMYS color under a given threshold, ensuring that the pattern is hidden under nonspecular viewing conditions. When the printing device requires the inks to be UV cured, the leafing effect of the silver ink is reduced. This also reduces the specular reflection of the silver ink, which becomes comparable to the specular reflection of the yellow ink. Since both specular reflections are similar, it is difficult to distinguish the embedded patterns under specular viewing conditions when both inks are present. The authors, therefore, propose a new algorithm to embed patterns in CMY images that not only maximizes silver but also minimizes yellow. Experimental results show that the proposed algorithm enhances the visibility of the patterns under specular viewing conditions, allowing the use of MetallicArt when the printing device requires UV curing. (C) 2011 Society for Imaging Science and Technology [DOI: 10.2352/J.ImagingSci.Technol.2011.55.6.060506]

XRF-Analysis of Fine and Ultrafine Particles Emitted from Laser Printing Devices

In this work, the elemental composition of fine and ultrafine particles emitted by ten different laser printing devices (LPD) is examined. The particle number concentration time series was measured as well as the particle size distributions. In parallel, emitted particles were size-selectively sampled with a cascade impactor and subsequently analyzed by the means of XRF. In order to identify potential sources for the aerosol's elemental composition, materials involved in the printing process such as toner, paper, and structural components of the printer were also analyzed. While the majority of particle emissions from laser printers are known to consist of recondensated semi volatile organic compounds, elemental analysis identifies Si, S, Cl, Ca, Ti, Cr, and Fe as well as traces of Ni and Zn in different size fractions of the aerosols. These elements can mainly be assigned to contributions from toner and paper. The detection of elements that are likely to be present in inorganic compounds is in good agreement with the measurement of nonvolatile particles. Quantitative measurements of solid particles at 400 °C resulted in residues of 1.6 × 10(9) and 1.5 × 10(10) particles per print job, representing fractions of 0.2% and 1.9% of the total number of emitted particles at room temperature. In combination with the XRF results it is concluded that solid inorganic particles contribute to LPD emissions in measurable quantities. Furthermore, for the first time Br was detected in significant concentrations in the aerosol emitted from two LPD. The analysis of several possible sources identified the plastic housings of the fuser units as main sources due to substantial Br concentrations related to brominated flame retardants.

A new wettability‐control technique for fabricating color OLED panels by an ink‐jet‐printing method

Abstract— The fabrication technique for color OLED panels by means of wettability‐controllable hole‐injection material (HIM) and a photocatalytic lithography method achieves both precise ink‐jet printing and long‐lifetime devices. The technique enables us to selectively change the non‐wetting surface of a hole‐injection layer (HIL) of metal‐oxide nanoparticles (MONPs) into a wetting surface without damage to the device performance. Wetting patterns formed by this method with photocatalyst‐coated photomasks made it possible to print emission material with patterns of precisely 98‐μm widths on the hole‐injection layer. A fluorescent green‐emitting device fabricated with an HIM of MONPs by the photocatalytic treatment exhibited a long lifetime of 365 hours at30,000 cd/m2, which can be extrapolated to a lifetime of more than 110,000 hours at 1000 cd/m2, assuming an acceleration coefficient of 1.7. A two‐color device and a monochrome passive‐matrix panel were also successfully fabricated. The two‐color device emitted light without the mixing of colors. The monochrome panel displayed alphabetical characters with good uniformity and no flaws.

Formation of conductive silver films via inkjet reaction system

A new method is described for conductive silver film formation. An inkjet printing device with two ink channels was used to deposit silver thin films. Two inks, silver ammonia and formaldehyde solutions, were separately ejected, mixed, and reacted on glass slides. The so-called silver mirror reaction created smooth and continuous silver lines of 90 micron in width with an average film thickness of 200 nm. Surface profilometry was used to measure the thicknesses and cross section areas of printed silver lines. The electrical conductivity of the resulting silver lines is 6% of bulk silver at room temperature. After sintering at 150 °C for an hour, electrical conductivity was enhanced to 14%. Scanning electron microscopy (SEM) showed that the microstructure of the printed thin films consists of nanoparticle grains of 50 to 200 nanometres. Results of X-ray diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDS) further confirmed our printed films purely comprised of face-centered cubic (FCC) silver crystalline. The printed conductive lines could be used for various applications, such as embedded printed circuit boards, micro-electromechanical systems (MEMS), and radio frequency identification (RFID) tags.

Portable microcontact printing device for cell culture

In this work, we developed a portable device to perform microcontact printing in a safety cabinet for cell culture. The device was designed to be small and non-bulky, easy to sterilize, while not requiring the use of electricity, and which requires very little manual handling. Moreover, the portable microcontact printer is reproducibly fabricated with a rapid prototyping system, and allows for the easy micropatterning of biomolecules with a resolution ranging from 20 to 500 μm. This opens new horizons in the direct and simple micropatterning of culture dishes and the mimicking and biofabrication of complex architectures of tissues.

이산 웨이블릿 변환과 명암도 동시발생 행렬을 이용한 컬러 레이저프린터 판별 알고리즘

고성능 저가의 디지털 인쇄기기의 출현으로 불법적인 위변조가 사회적인 문제로 대두되고 있고, 이를 해결하기 위해서 디지털 포렌식 기술이 필수적이다. 본 논문에서는 컬러 디지털 인쇄기기를 판별하기 위한 디지털 포렌식 기술을 제안한다. 컬러 디지털 인쇄기기는 제조사마다 인쇄방법이 다르기 때문에, 출력물에 작은 차이가 존재한다. 이와 같은 차이점을 활용하면, 임의의 주어진 출력물에 대해 어떠한 인쇄기기로 출력되었는지 구별이 가능하다. 제안하는 방법에서는 차이점을 구별하기 위하여 출력물을 스캔한 디지털 이미지에 대해 이산 웨이블릿 변환을 수행하여 계산한 고주파 영역을 추출한다. 이에 대해 명암도 동시발생 행렬을 계산한 후에 행렬 데이터의 표준편차, 첨도, 왜도, 공분산, 상관계수의 특징을 추출하였다. 추출된 특징을 서포트 벡터 머신 분류기에 적용하여 디지털 인쇄기기를 판별하였다. 제안한 알고리즘의 성능을 분석하기 위하여 총 2,597장 이미지와 7대 프린터(HP, Canon, Xerox DCC400, Xerox DCC450, Xerox DCC5560, Xerox DCC6540, Konica)를 가지고, 기존 알고리즘과 비교 분석하였다. 그 결과에 따르면 제안한 알고리즘은 컬러 디지털 인쇄기기를 판별하는데 있어서 평균 96.9% 정확률을 보였다. High-quality and low-price digital printing devices are nowadays abused to print or forge official documents and bills. Identifying color laser printers will be a step for media forensics. This paper presents a new method to identify color laser printers with printed color images. Since different printer companies use different manufactural systems, printed documents from different printers have little difference in visual. Analyzing this artifact, we can identify the color laser printers. First, high-frequency components of images are extracted from original images with discrete wavelet transform. After calculating the gray-level co-occurrence matrix of the components, we extract some statistical features. Then, these features are applied to train and classify the support vector machine for identifying the color laser printer. In the experiment, total 2,597 images of 7 printers (HP, Canon, Xerox DCC400, Xerox DCC450, Xerox DCC5560, Xerox DCC6540, Konica), are tested to classify the color laser printer. The results prove that the presented identification method performs well with 96.9% accuracy.

Study of the Effect of Coating Thickness, Substrate Temperature and Biasing Voltage on Various Characteristics of AlN Film

AlN thin films have a wide range of applications in electronic devices. AlN thin films are used as a protective coating of thermo printing devices and also as a material of cold cathodes. Moreover, these thin films are the most promising piezoelectric materials for surface acoustic wave (SAW) applications. In this work, thin films of AlN were grown on glass and MS substrates by reactive DC magnetron sputtering. The crystallographic and micro-structural properties of sputtered AlN films were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The films were found to be having hexagonal crystalline AlN structure in all cases irrespective of deposition parameters. However, Al peaks were also observed showing simultaneous metallic layer deposition. Grain growth was observed with increase in film thickness. Biasing resulted in better adhesion of the nitride film with the substrate. Hardness measurements were also made for different deposition parameters, but less significant changes were observed.

Prediction of results from subjective evaluation of real-time-capable tone-mapping operators applied to limited high-dynamic-range images

The dynamic range of digital image sensors is growing faster than the reproducible dynamic range of standard display and print devices. In an assessment, we evaluated eight real-time-capable, high-dynamic-range (HDR) tone-mapping operators, using HDR images restricted to 12 bits per channel, and mapping to 8-bit low-dynamic-range (LDR) output data. In our survey, 51 test persons rated the subjective quality of LDR images of 15 scenes. For each scene, the operators were tested against linear tone mapping. From that survey, we derived three operators that performed better than linear mapping and evaluated their impact on exposure when using tone-mapping in an imaging chain. To mathematically predict the subjective quality of tone-mapped images, we tested five figures of merit against the empirical results of the survey. We propose a quality measure derived from the Naka-Rushton equation. We evaluate the proposed metric against four other image quality metrics, with our novel measure matching the subjective results best.

An application of ESD technology for the R2R printing process

The conductive coating method is used for various industrial fields. For example, the sputtering process is used to coat the ITO layer in LCD or OLED panel manufacturing process and fabricate a base layer of substrate of an electric printing device. However, conventional coating processes (beam sputtering, spin coating etc.) have problems in the industrial manufacturing process. These processes have a very high cost and critical manufacturing environment as a vacuum process. Recently, many researchers have proposed various printing processes instead of conventional coating processes. We propose an ESD printing process in ITO coating layer and apply to fabricate a conductive coating film. Furthermore, the effect of the nozzle and also the applied voltage on different configurations of the nozzle head was also studied for better understanding of the electro static deposition process.

Rib-free Ink-Jet Printing Fabrication on Heterogeneous Surfaces

Rib-free ink-jet printing device fabrication on hetrogeneous surfaces opens a new possibility for greener processes. The integrity of ink droplets was maintained with less than 3° contact angle differences on the heterogeneous surfaces after surface treatment. The breaking of color lines and color mixing were avoided by accelerating solvent evaporation. The inks were greatly conserved without the need for additional lithography process for rib structure.

Least-Squares Halftoning via Human Vision System and Markov Gradient Descent (LS-MGD): Algorithm and Analysis

Halftoning is the core algorithm governing most digital printing or imaging devices, by which images of continuous tones are converted to ensembles of discrete or quantum dots. It is through the human vision system (HVS) that such fields of quantum dots can be perceived to be almost identical to the original continuous images. In the current work, we propose a least-squares-based halftoning model with a substantial contribution from the HVS model, and we design a robust computational algorithm based on Markov random walks. Furthermore, we discuss and quantify the important role of spatial smoothing by the HVS and rigorously prove the gradient-descent property of the Markov-stochastic algorithm. Computational results on typical test images further confirm the performance of the new approach. The proposed algorithm and its mathematical analysis are generically applicable to similar discrete or nonlinear programming problems.

Mechanism of electrohydrodynamic printing based on ac voltage without a nozzle electrode

The electrohydrodynamic (EHD) spraying technique has been applied to inkjet printing technology for fabrication of printed electronics. The conventional EHD inkjet device is based on dc voltage and requires two electrodes: a nozzle electrode and an extractor electrode. This study notes several drawbacks of the dc-based EHD printing device such as electrical breakdown and demonstrates stable jetting by using the extractor electrode alone without the nozzle electrode and ac voltage. The continuous ejection of droplets can be obtained only by ac voltage, showing consistent ejection at every peak of electrical signal. The suggested EHD inkjet device prevents electrical breakdown.