An Analysis of Moisture Transportation within Paper in the Fusing Process of Electrophotography

概要

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Paper curl causes paper jam or print quality degradation in electrophotographic printers and copiers. It is useful to predict amount of the paper curl in electrophotographic process for the efficient products development. The fusing process which is a sub-process of electrophotography is one of the causes of the paper curl. But it had been unclear how the paper curl was generated in the fusing process. In a previous study, a paper curl mechanism based on temperature gradient in paper heating was revealed. The mechanism shows that a temperature gradient causes moisture transfer from the high-temperature side to the low-temperature side within paper and consequently the moisture content of the low-temperature side becomes higher than that of the high-temperature side. This causes a shrinkage difference between both sides of the paper and thus the paper curl is generated. In this report, a one dimensional numerical model to simulate moisture transfer within paper is proposed. In this model, paper is treated as a uniform porous material and the moisture diffusion and transfer are treated according to Darcy's law, as well as evaporation during heating. The computer simulations are carried out to determine the moisture distribution within the paper when the surfaces are heated at different temperatures. The results are finally verified by measuring electrical resistance of papers. They are found to be in good agreement.