A new model of charge generation process in the single layer organic photoconductor (OPC) was proposed where the charge generation took place at the surface of the photoconductive layer after phonon diffusion from within the photoexcited bulk photoconductive layer. The degradation of the edge sharpness of the electrostatic latent image was simulated theoretically according to this model and the parameters that dominated the resolution degradation in the single layer OPC due to the energy diffusion were determined. The analytical result suggested the model of edge degradation in this system depended strongly on the phonon diffusion length. Accordingly, an experimental analysis was performed that explained the dependence of diffusion length on the photoreceptor formulation. The experimental result showed the validity of the principle in the proposed model for all OPC formulations tested, and the existence of a significant dependence of diffusion length on the CGM concentration in the photosensitive layer. The obtained results numerically showed the superiority in resolution of the single layer OPC compared with those of the conventional dual layer OPC, suggesting the possibility of true 2400 DPI imaging. The results provided a guideline for realizing higher resolution imaging via the single layer OPC formulation.

The authors have revealed that paper having high smoothness, small pore size, and low drying ability is suitable for discoloring decolorable toner. In the heat erasing process, water accelerates the dissociation of leuco dye and developer and/or the diffusion of developer, considering the high dielectric constant of water and the solubility of developer in water. The authors have confirmed diffusion of the developer into paper from the toner in the heat erasing process by the direct evidence and results of energy dispersive x ray and time-of-flight-secondary ion mass spectrometry.

The authors have developed a highly effective image eraser for decolorable toner that comprises leuco dye and developer. Using a heat eraser requiring minimal, printed paper with decolorable toner can be reused repeatedly. However, the erasing is visible in spite of discoloring because of the binding resin remaining on the paper. The new image eraser employs an erasing process consisting of rubbing, dust cleaning, and heating. The processes cause the original image to completely disappear. This method achieved both complete destruction of the printed information and renewal of the used paper. A paper can be reused at least five times in the case that the erasing condition is such that the original image completely disappears. This paper describes the mechanism of the erasing processes.

Printer banding which appears as nonuniform light and dark lines across a printed page have been an important image quality issue in the printing industry, and have been studied by many researchers. However, no literature has reported banding perception in different printers with different characteristics of banding. In this paper the authors develop a tool for measuring banding based on human perception. The authors describe new cross-platform experiments using ten different laser printers having different imaging characteristics. In order to focus on the impact of the printer mechanism on banding and to remove the confounding effect of the halftoning algorithm, the authors employ a specially designed line screen with all the test printers. The authors use the pulse width modulation capability of a single reference printer to match the absorptance of these printers, and to also generate extrinsic banding signals. The experimental results identify the points of subjective equality of the ten printers relative to the banding of a reference printer, and provide the basis of a method of computing banding power by considering a contrast sensitivity function. The authors results show that regardless of the different banding spectral characteristics, the contrast banding power of a given printer can be mapped to a perceptually equivalent level of contrast banding power of one reference printer with added extrinsic banding.

An improved controller design and implementation technique for electrophotographic process (EP) was proposed. The new controller aimed at solving two additional issues for generic EP platforms, i.e., reducing position-dependent or spatially periodic disturbances, and reducing system sensitivity to manufacturing variations in EP engine and consumables. To handle spatially periodic disturbances, a digital repetitive controller was synthesized and implemented using a spatial-sampling scheme. The result is a control algorithm that takes into account the variation of the nominal operating speed. Second, system variations due to manufacturing variations as well as consumable changes were incorporated into the design of a two degree of freedom robust controller. The controller is optimal in the sense that it minimizes the size of the sensitivity function from a set of disturbance signals to a set of measurable signals critical to print quality, e.g., photoconductor drum velocity or scan line spacing. A suitable trade-off between system performance and robustness to system modeling uncertainties was considered in the synthesis and optimization formulation. The effectiveness of the proposed controller design and implementation technique was numerically and experimentally verified. Significant reduction in visible banding was seen in printed images and was verified by reflectance measurement.

The aim of this paper is to illustrate the use of gloss effects for security printing. These gloss effects can be produced using pigmented ink jet inks. The main reason for using this type of artifact for security printing is that the effects can be made invisible to typical desktop scanners while still remaining readable by the human eye and machine reading systems. The two gloss effects investigated are differential gloss and gloss color. In both cases, methods of visualizing and measuring these are considered with examples. The paper continues by giving examples of some of the variables that can be used to make this a secure system and concludes with a series of photomicrographs examining the root cause of these effects.

Nonaqueous ink jet inks and their long-time stability at different temperatures were studied using single particle optical sensing (SPOS). Samples ground for the same period but having different amphiphilic polymer additives used for steric stabilization were prepared. SPOS characterizes the particle size distribution at the high end of the particle diameter (>0.5 μm.). In the aging at different temperatures, the high-end size distribution exhibited changes ascribed to sedimentation and aggregation. In the absence of aggregation, the decrease of the particle volume was identified as originating from sedimentation; the dependence on particle diameter and solvent viscosity agreed with theoretical prediction. The aggregation appeared as a hump in the tail of the main peak in the size distribution. The hump was apparent for inks aged at a higher temperature and having more loosely adsorbed polymer additives.

Based on recent progress, nonimpact printing techniques can deliver the next generation of materials for an extensive set of novel applications. A novel hot melt ink composition, useful for three-dimensional (3D) printing comprising different waxes, tackifier and plasticizer resins, rheology modifiers, and gas releasing agents, was designed. The behavior of the inks was comparable to commercial hot melt inks without gas releasing agents. The hot melt ink properties promise a possibility of use in a conventional phase-change printer in order to create 3D printed structures. Differential scanning calorimetry was used to evaluate thermal properties of the ink components and the extensive study of the thermal behavior of the proposed gas releasing agents has been carried out. The rheology behavior of inks was measured, and printability analysis, such as image detail, definition of dots (height, sharpness of the edges), dot formation, and spreading were investigated. Rub resistance tests were also used together with tape adhesion tests for ink adhesion monitoring.

Two distinct approaches for updating a CMYK printer model in response to systematic changes in print device behavior are presented. In the first method, a corrective model is constructed from a sparse set of newly acquired characterization data and used in addition to the initial printer model. A number of corrective models are investigated, including linear, quadratic, and artificial neural network models. The second method involves directly updating the parameters within the printer model. The updated model parameters are obtained using both the original characterization data and a set of newly acquired data. Both methods are evaluated in a set of experiments in which either the paper stock or the cyan toner cartridge is changed. The corrective model approach is found to be the most effective. The most successful corrective models removed between 76% and 100% of the systematic error.

Gloss meters are commonly used to measure characteristics of the specular light reflected from materials. Such meters are based on illumination and detection at equal, opposite angles. The particular angle, , and other parameters of instrument geometry, are well known to play major roles in the results produced by a given meter, so several standards have been developed for gloss measurements that specify the geometry and optical characteristics of gloss meters (TAPPI T480; ISO-2813 (1994); ASTM-D523-89 (1999)). Nevertheless, the reason why gloss meter readings change with , and the reasons why meters of the same  produce different readings seem not to be well understood. The focus of the study described in this paper has been on exploring these two effects. A quantitatively model of a generic gloss meter was constructed from Fresnel's law of surface reflection combined with empirical models of bidirectional reflectance distribution function (BRDF). Comparison of the model with experimental data strongly indicates that the width of the BRDF, and therefore the roughness of the surface, plays the major role in governing the reading from a gloss meter. Differences in index of refraction, by comparison, appear to play only a minor role. In addition, differences in gloss readings produced by instruments of the same angle, , were found to be the result of differences in the instrument angles of acceptance. The results of these studies suggest that it may be possible to make better use of conventional gloss meter measurements by making measurements at multiple angles, , rather than just a single angle.