Spectrophotometers to measure object-colors are generally divided into two types of measuring geometry as 45-degree, 0/45, and integrating sphere, d/8, and the latter is furthermore classified into two modes, namely, specular component include (SCI) and specular component exclude (SCE). However, according to the difference of these types of measuring geometry, each colorimetry result with the same sample can be considerably different from others, because of the influence of the component reflected normally from the sample surface. This will cause extremely confusing matters, in particular, if a dark sample is glossy. In this article, we have examined the differences of metric-lightness with these geometric conditions, and come to the conclusion that any measured result for glossy samples should be related to a correlation of gloss in order to match human perception under a common viewing condition, that is an illuminated environment of a general office. And furthermore, we have proposed an estimation model that gives a visual lightness for object-colors, which is independent of different kinds of measuring geometry.

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We have developed a novel color-fusing system “Free Belt Nip Fuser (FBNF)”. This fuser uses small heat capacity fuser roll, thin belt and stationary pressure pad in it. Pressure pad forms wide nip with low pressure and high pressure at nip exit. By optimization of nip pressure profile, good fusing performance is obtained. And this nip pressure profile makes micro-slip between fuser roll surface and toner at nip exit, and achieves good stripping performance in case of thin elastic layer of fuser roll. Compensation of fuser roll bending by use of stationary semi-cylindrical pad makes possible to use small diameter and very thin fuser roll. Further, combination of semi-cylindrical pad and straight belt prevents paper wrinkles in nip. By introducing these technologies into fuser, FBNF achieves short warm up time and realizes energy-saving color fuser.

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Liquid toner electrophotography previously suffered a problem whereby the quality of color toner images were degraded in the transfer process. In the new transfer method adopted to solve this problem, the developed and accumulated color toner image on the photoreceptor will be carried through two steps. In the first step, the color toner image is moved onto the intermediate transfer media under the shearing and pressing stresses, without fusing to be film. In the second step, the color toner image is moved onto the paper by the sticking force of itself, which has arisen under the heated and pressed conditions. By using this non-electrostatic transfer method, liquid toner electrophotography shows its best performance. The transfer phenomena and its characteristics, however, are not sufficiently understood. We attempted to analyze the dynamics of the elastic material used for the intermediate transfer media. Our conclusion is that elastic and frictional forces work more effectively than tacking forces among the materials in this transfer process.

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In the image-on-image (IOI) color process using liquid toner, the toner image developed on the photoreceptor includes excess solvent. The optimum drying condition of the toner image is required to realize highly efficient transfer by using non-electrostatic transfer. The authors have found that the drying state of the toner image can be monitored by measurement of the reflective intensity of the laser beam irradiated on the toner image surface with solvent evaporation. In this paper, we discuss the relationship between drying states and transfer performance, and the adhesion force of toner image to the transfer drum and to the photoreceptor is evaluated. The drying states in the optimum range obtained the highly efficient transfer were investigated by measurement of toner concentration and observation by Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM). The experimental data were confirmed by evaluation of the adhesion force.

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The characteristics and stability of the corona discharge is influenced by atmosphere. In this report, the influence of hydrocarbon on the corona discharge is investigated. When airflow containing hydrocarbon is supplied to the corona discharge area, the corona discharge is suppressed in both polarity cases and the increase of the voltage to maintain constant current occurs. The main suppression mechanisms of the corona discharge are estimated to be the accumulation of hydrocarbon on wire in negative case, and the absorption of ultraviolet light by hydrocarbon in positive case.

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We developed a novel 1200 dot per inch light emitting diode (LED) print head for a high quality digital color printer in the next generation. The LED print head was really suitable for a high speed color printer. In order to achieve the high performance of the LED print head, we developed an original 1200 dpi LED array chip with matrix structured wiring. Moreover, the LED array chip made “Low cost LED print head” which the number of bonding wire and driver integrated circuit chips on the LED print head decreases below a half, compared to the conventional 1200 dpi print head.

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[in Japanese]

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