Academic literature on the topic 'Print unevenness'

Having been coated, the surface unevenness and pores on paper were covered by a coating layer composed of fine particles and binders, which can absorb ink well, thereby a good uniformity and smoothness of paper could be obtained, consequently, the reproducing capability for printing dot and good whiteness, gloss and opacity can be improved. In theory, the ink rub resistance for coated paper print is mainly affected by the ink absorbance property of paper, printing conditions, ink components, rub medium and so on. In this study, seven different kinds of coated papers, the viscosities of the inks were adjusted with a viscosity adjusting agent, and then the prints were prepared by proofing with the ink with different viscosities. After drying, the prints were used for rub testing. The impact of the basic properties of coated paper and the content of reducer in inks on rub resistance were discussed on the basis of a comparative analysis of the experimental data. Printing color density loss rate and print color difference were exploited in this paper to characterize the ink rub resistance for coated paper prints. In this study, it was found that ink rub resistance was mainly influenced by ink absorbency and smoothness of the paper. Under the similar conditions, the color density of coated paper print decreases with the rub strength increasing, color difference increased gradually, but not linearly. With the increase of ink viscosity reducer content, printing density loss rates as well as color difference changed, but not be linearly.

Mesin 3D printer adalah mesin pembuat suatu model 3D. Metode mesin 3D printer yang digunakan pada Fakultas Teknologi Industri Universitas Trisakti adalah metode FDM (Fused Deposition Modelling). Diketahui adanya ketidak stabilan pada meja cetakan mesin 3D printer pada saat proses produksi dilakukan. Ketidak stabilan meja cetakan mesin 3D printer, menyebabkan tidak maksimalnya produk yang dihasilkan. Terdapat perbedaan antara hasil produk dengan bentuk produk yang telah di desain sebelumnya. Setelah diteliti lebih lanjut, ketidak rataan pada meja disebabkan pada pengaturan meja cetakan yang kurang sesuai. Hasil dari redesain dapat menstabilkan meja cetakan dan memudahkan untuk melakukan kalibrasi dan pengaturan pada meja cetakan mesin 3D printer. Hal ini terbukti ketelitian dimensi produk hasil cetakan yang meningkat dari penyimpangan terbesar 0,037 mm menjadi 0,069 mm, yang diukur dengan proyektor profil yang mempunyai kecermatan 1 mikrometer. 3D Printer Machine is a 3D shaped model making machine. The method of 3D printer machine used by the faculty OF Industrial Technology of Trisakti University is FDM (Fused Deposition Modelling) method. There is known unevenness on the build plate of 3D printer machines during the production process. The unevenness that appears on the objects makes the build plate used by the 3D printer engine unstable. This causes the product to be produced not maximal. There is a difference in shape between product results and previous product design. After further investigation, the unevenness of the table was caused by the improper arrangement of the printed table. The results of the redesign will stabilize the print table and make it easier to calibrate and adjust the print table of the 3D printer machine. This proven that precision of product dimension increase from 0,037 mm deviation to 0,004 mm, its measured with a profile projector has 1 micrometer resolution.

Abstract Print mottle is observed as an unevenness of printed tone across an image area. There are many causes of mottle on typical print media, i.e. printing and writing papers, packaging and board, as well as foils and polymer surfaces amongst others, in both applications of traditional printing techniques, such as offset and flexography as well as digital methods, including inkjet and electrophotography. Causes range from inhomogeneous surface chemistry and absorption characteristics to instability factors on the printing press. Since the phenomenon is both physical and aesthetical, providing an evaluation for comparison purposes is challenging, frequently requiring panels of observers to provide a visual ranking. A new evaluation method is proposed using wavelet denoising and grey level gradient analysis of the print image. The index of print mottle is built on the bases of the average of grey level gradient and its distribution standard deviation. The method was tested for print mottle evaluation on paper in specific situations under different image basis functions and decomposition level. The results show that the method is in good agreement with visual assessment, and is also less time consuming both in the process and in statistical analysis, with correlation coefficient (r2) of at least 0.79 and as high as 0.88 with every function basis (level 2 or 3).

Les travaux présentés dans cette thèse ont permis de clarifier le potentiel des fibres recyclées (RCF) et les limites rencontrées dans la fabrication de papiers magazines Super Calandrés (SC). La pâte recyclée contribue à améliorer densité d'impression et homogénéité des aplats en héliogravure mais tend à détériorer diffusion de la lumière, transvision, marbrage et points manquants. L'origine des différences observées entre les papiers à base de RCF et ceux à base de fibres vierges a été étudiée en simulant les effets de la composition fibreuse, du recyclage et du raffinage sur la qualité des papiers SC. Le taux de fibres chimiques s'est révélé être un paramètre influençant la plupart des caractéristiques des SC, dont transvision et marbrage. Par contre le taux de fibres mécaniques à paroi cellulaire épaisse a un effet marginal sur la qualité des papiers SC. La tendance vers une augmentation des points manquants lorsqu'un papier SC à taux élevé de pâte recyclée est imprimé en héliogravure a partiellement pour origine le raffinage de la RCF à haut niveau d'énergie spécifique
Based on industrial experience of UPM mills and advanced pulp and paper analysis, this thesis has aimed to clarify the potential and limitations of recycled fibres (RCF) for Super Calendered (SC) magazines and recommend future developments in fibre processing technology. RCF is found to improve SC print density and evenness in Rotogravure but tends to deteriorate light scattering, print through, calender blackening and missing dots. The origin of the differences observed between virgin fibre and RCF based SC has been studied by simulating the effects of fibre composition, recycling and refining stages on SC paper quality. Chemical fibres content turns out to be a parameter driving most of SC characteristics, including print through and calender blackening. Conversely, the presence of coarse mechanical fibres within RCF was found to have a marginal effect on SC paper quality. Finally, the trend for more missing dots when printing RCF compared to virgin fibres based SC originates at least partially from high energy RCF refining

Abstract Printed electronics is a technology in which conductive ink or functional materials are printed as a flexible material passes between rolls. It is possible to apply various applications such as solar cell, sensor, and display, and it is the next generation process that can mass-produce eco-friendly within a short time. However, if the printing pressure between rolls cannot be made uniform in a roll-to-roll process, it is difficult to commercialize printed electronics due to the deterioration of print quality. In our previous work, initial conditions were selected using pre-measured roll shape information to minimize printing pressure variations, and the printing pressure unevenness due to repeated runout was reduced. In order to equalize the contact printing pressure, this paper designs a controller model similar to the half car model considering the relationship between the two servomotors of the two degree of freedom individual drive system and the pressures at both ends of the impression roll. In addition, the control system to uniform the contact printing pressure using the roll-to-roll two degree of freedom individual drive system was confirmed by simulation and experiment.