抄録
Intermediate transfer belt plays a very important role in electrophotographic devices like color printers and copying machines to transfer the toner from the photoconductive roll to the paper. Polyimide film mixed with carbon powder is often used as the material of the belt. The toner is attached by electrostatic force. However, the transcription mechanism has not been investigated sufficiently. We examined the mechanism by the observation of space charge behavior under dc voltages. A significant space charge was observed in the vicinity of the front surface on which the toner is attached in the practical device. This would enhance the electric field on the surface and consequently upgrade the transcripting performance. The surface resistivity was higher on the front side than the rear side, leading to the formation of large space charge in the vicinity of the front surface. Three dimensional space charge measurement showed that sectional distribution of surface resistivity strongly influences on the formation of the space charge and determines the quality of the printout. The intensity of the space charge became larger with increasing dc voltage, however, dielectric breakdown took place when the voltage was extremely high. It is recommended that the applied voltage across the film should not be higher than the region in which the leakage current rapidly increases. Ion analysis showed the existence of organic acid, suggesting that the space charge was formed as the result of its dissociation.
