Dynamic triboelectric charging behaviors of polymer films in contact with meta-plate and non-plated iron carrier beads were investigated under controlled atmospheres. Saturated surface potential(Vs) and humidity dependence (S) of the polymer films were dependent on the measured work function of the carrier beads (φ): the values of Vs and S were increased with decreasing φ, indicating that the tribo-charging is described by electron transfer at a metal/Polymer interface. The charging model to account for these results was presented; it assumed the existence of an electrical double layer formed in the vicinity of a film surface by penetration of charged water molecules and of electron-acceptive sites inherent in polymer materials.
Further investigation on the effect of humidity suggested that the charging characteristics of the polymer films were determined by humidity dependent properties of carrier and polymer materials, but the effect was mainly exerted on the polymer film if its polar nature is relatively large.

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The title compound is a commercial black pigment based on the perylene skeleton. As evaporated, it exhibits a brilliant red color (absorption maximum: 500 nm). However, it undergoes a color change from red to black (absorption maxima: 473 and 610 nm) when exposed to acetone vapor or heated above 100 °C for several seconds. The electronic spectra have been characterized on the basis of the crystal structure and intermolecular interactions. The red color (500 nm) is due to randomly-oriented, individual molecules in the amorphous phase ; whereas the black phase is characterized by a quasi-ordered system which gives two absorption bands: one is due to individual molecules (473 nm) and the other is due to exciton coupling effects (610 nm). The color change is attributed to the appearance (“on” state) or disappearance (“off” state) of the absorption band around 610 nm and is applicable to optical disk systems based on an AlGaInP diode laser of 635 nm. An information storage system has been developed in which the absorption at 635 nm is switched on (red —> black) or switched-off (black —> red) on irradiation with laser in the presence of a hydrazone compound that induces a phase change.

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A visual experiment was performed to evaluate the effect of black separation on spatial image quality. Two types of black printer algorithms were evaluated. One simulated conventional printing with the exception of yielding colorimetric matching. The other employed a simple algorithm based on minimum and maximum amounts of black and also employed a colorimetric paradigm. Using pictorial and synthetically generated gradation images,two visual experiments were performed. For pictorial images, the simple algorithm resulted in the highest spatial image quality. However, this algorithm produced color contours, visible in the gradation images. Thus for general purposes, the conventional separation algorithm or the simple algorithm using nearly the minimum black amount is recommended. From the two experiments, it was pointed out that there was significant difference among black printer algorithms in perceptibility criteria of spatial image quality, even though there was no significant difference in acceptability criteria.

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