To advance the applications of electrostatic particle control technology, it is important to investigate the behavior of the particles in an electric field. In this study, the behavior of conductive particles between two horizontal parallel plate electrodes, one of which was covered with a sheet of paper, was observed with a high-speed camera. It was found that the particles started to jump from the electrodes when the applied voltage exceeded a certain value, and when they touched the paper-covered electrode, they stayed on there for some time before they left for the other electrode. It is considered that because of the lower electric conductivity of the paper than that of a metal, they take time to change the sign of their electric charge and jump toward the other electrode. It has been found that their staying time on the paper-covered electrode becomes shorter as the applied voltage increases. This phenomenon can be explained by the relation of the time required for arriving to the charge for particle jump and the intensity of the applied electric field.

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Regarding image quality improvement of xerographic prints, it is important to obtain high-definition latent images. When a laser scanner is used to form latent images on a photoreceptor, an optical design to obtain a small beam is required. In order to make the beam finer, it is necessary to reduce the effect of diffraction, which is realized by increasing the convergent angle to the photoreceptor. A larger angle makes the depth of focus shallower. Hence, it is more difficult to focus the beam on the entire photoreceptor surface, and optical components must be assembled precisely. In this research, we carried out a beam profiles simulation considering both diffraction and aberration in a laser scanner optics. The effect of aperture shapes on beam profile is discussed applying the simulation.

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The 3d numerical procedure to simulate Toner Display device had been constructed which is one type of electric papers using insulative charged toners. The simulated results were compared to the experimental results in L8 test space and the results agreed quantitatively at 0.83 correlation coefficient. It was also confirmed in this investigation that the distance between driving electrodes and dielectric layers on the electrodes affect displayed image quality and that the attractiveness of dielectric layers have significant effects on the quality. In addition, the passive driving process was simulated well qualitatively. This 3d numerical procedure is expected to be a useful tool to improve the quality of Toner Display device.

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We developed a new rewritable system which is composed of coated paper, microbial ink derived from the fermatation of Monascus fungi and fading process using discharge. The loss of chromophore in monascus dye is attributed to electrophilic reaction by oxidation gas, i. e., ozone. The present work systematically investigated the fading phenomena of monascus dye using the corona, the creeping, and the dielectric barrier discharge treatments. From the experimental results, we note that: (I) the fading time using the creeping discharge treatment is faster than that of the corona discharge, because the ozone concentration generated by the creeping discharge is about two times compared with the corona discharge, (II) the light irradiation during discharge treatment is more effective in a fading process, (III) the fading performance on the dielectric barrier discharge is effected by the dielectric constant, and the secondary electron emission coefficient of the dielectric material, (IV) the print on coated paper exposed to the dielectric barrier discharge has a fading time of 1 s or less.

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Charge control capability of trianilino-triphenylmethane (TATPM: a positive type CCA (P)) for styreneacrylic (St-Ac) model toner is evaluated using two types of two-component developer samples. One of the samples is a mixture of St-Ac model toner T_P which has a TATPM coating layer on its surface and a ferrite carrier C, and the other is a mixture of CCA-free St-Ac model toner T and a ferrite carrier C_P which has a TATPM coating layer on its surface. The toner charge q/m in the T_P-C and T-C_P combinations is measured by a blow-off method. Both toners separated from the developer of the T_P-C combination and that from the developer of the T-C_P combination show a positive charge. By a colorimetric method, after the mixing process, it is confirmed that small amount of TATPM adheres on the C surface (in the T_P-C combination) or T surface (in the T-C_P combination). Therefore the TATPM layer coated on the T_P surface or C_P surface is peeled off by a mixing operation as a TATPM particle. From the above results, it is confirmed that, in the toner charging of the two-component developer of the T_P-C or T-C_P combination, the TATPM particles from the TATPM coating layer of the T_P or C_P surface serves as a positive charge messenger.

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In recent years, many kinds of digital imaging systems have been developed and achieved high accurate color reproduction and image quality. Color reproduction of these imaging systems are based on the three primary color mixture, namely additive color mixture RGB and subtractive color mixture CMY. In this paper, those conventional color reproduction and spectral based color reproduction are described.

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Recently we have seen an increase in interest in constructing image processing workflow based on analysis of scene content. In this report, I introduce a camera system capable of acquiring colorimetric images of a scene, the color reproduction gamuts for scenes each containing highly color-saturated reflective objects, fluorescent objects, or semi-transparent objects measured by the system, and examination about image reproduction method for scene images.

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In the printing industry, the trouble about color-reproduction in the printing work flow and the request level about color-reproduction have changed by popularization of the digital device. The client makes a request to print the same color-reproduction as the color monitor and the color printer, and to print anytime and anywhere by the same color reproduction. From such a background, this text explains the printing color standard in Japan, and challenge of wide color-reproduction in printing.

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Monochrome electrophotographic printers are increasingly replaced with full color ones every year. The full color replacement started from the printing and designing segment and also in the office equipment segment, not only full color single function printers but also multifunctional full color printers have been accepted. Currently, printer manufacturers come to have them as their core product portfolio. This paper describes the characteristics of electrophotography accompanied by the full color replacement and technical measures for emerging issues.
The points of color creation in the electrophtograpy are “color stability”, “color gamut” and “color arrangement”. We should go by requirement specifications for offset printing prioritized because of its large-volume paper handling. We should also go so far as to consider measures ranging from photographic output to multimedia systems such as static or moving images observed in the PC displays.

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[in Japanese]

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Recently we see the imaging devices which provides wider gamut than sRGB in market. Regarding display devices, wide gamut displays also available now, thanks to advanced technologies of materials or related technologies, study result of their use has already reported by certain group.
This paper describes technical background of wide gamut displays, technical issue, i.e. relation with color matching function and color management, examples of development, and applications and next steps.

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Imaging advances in very high resolution computer-to-plate technologies have enabled the stable rendering of microdots and pioneered a worldwide increase in printing with frequency modulated
(FM) halftone screens. This paper defines various forms of FM, AM and hybrid screening technologies and evaluates their strengths, weaknesses and potential benefit to printing.

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