Polystyrene (PS) films were doped with electron-donating and electron-acceptive dopants, and their triboelectric charging behaviors when charged by contact with iron carrier beads were investigated under controlled atmospheres. Saturated surface potential (Vs) of the PS films was shifted to positive direction and the humidity dependence of Vs was decreased by the doping of donor dopants, while acceptor ones brought about the reverse changes. The magnitude of such changes in the charging characteristics seemed to be related to the length ofπ-conjugated systems of the dopants.
PS films doped with1-aminonaphthalene, AN (5-aminoquinoline, AQ) and 1-nitronaphthalene, NN (6-nitroquinoline, NQ) were compared with films doped with 1-amino-4-nitronaphthalene, ANN (5-amono-6-nitro-quinoline, ANQ). It was found that the charging behavior of the former films were govemed by the donor dopants (AN or AQ), while in the latter films electron acceptive groups also contributed to the triboelectric charging.
In addition, the effect of relative positions of electron-acceptive and electron-donative groups of the dopants on charging behaviors was examined using PS films doped with nitroaniline and nitropheno1, and it was revealed that the humidity dependence increased in order of o-<m-<p- positions.

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A high resolution image can be made by laser dye thermal transfer printing because of the high converging property of a laser beam. In this paper, in order to clarify the process of dye transfer and dot formation, the microscopic configuration of the printing media was measured by AFM (Atomic Force Microscope) and temperature change and temperature distribution were analyzed by numerical calculation.
As a result, the ink sheet and accepting paper expand and push each other during the process of dot formation. The expansion of the printing media and the start of dye transfer were explained by the characteristics of the temperature change in the media. Furthermore, thermal response at the under surface of the ink layer was analyzed using simplified model of two order lag system.

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A new imaging system by using a sleeveless magnet roller was developed. The sleeveless magnet roller developing system is aimed to be simple by elimination of sleeve and flange from conventional magnet roller. The sleeveless magnet roller was made of a sintered ferrite magnet of 20 mm in diameter, magnetized with 16 or 32 poles.
The sleeveless magnet roller developing system gave high quality print images at the distance of 0.1 mm between the developing gap and the doctor blade gap nearly same as those by a conventional sleeve rotation system. The developer with magnetic toner and iron particulate carrier could print out an excellent print sample with a wide available toner concentration range of 20 to 70 wt%. Magnetic toners, which contained magnetite particles 10 to 50 wt% gave a high image density and excellent print sample. On the other hand, the developer with non-magnetic toner and iron particulate carrier gave the good print sample at the toner concentration range of 10 to 60 wt%. The available toner concentration range for the new sleeveless system was found to be much broader than the conventional dual component sleeve rotation system. The bias voltage dependence of the image density by the new system was similar to that by non-magnetic mono-component developing system. The high image density by the new sleeveless developing system was continued for more than10,000 copies for both magnetic and non-magnetic toners,

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