電子写真の定着過程におけるカール解析

抄録

Paper curl is a paper handling problem that occurs in electrophotography based printers and copiers, and leads to paper jam and degradation of the print quality. Some of the reasons for paper curl are shrinkage of the resin toner after the fusing process and bending during paper transportation, and these have been the subjects of several studies. Another reason for paper curl is paper heating during the fusing process. A fuser has a heating roller that bonds the toner to the paper and a pressure roller that presses the paper against the heating roller. The temperature difference between these two rollers is what leads to paper curl. Although some experimental studies have been carried out on this effect, it is still not sufficiently well understood. In the present study, an experimental apparatus is used to press a sheet of paper between two flat heated plates. It also allows the absolute humidity of both paper surfaces to be measured, in addition to the degree of shrinkage and the stress relaxation percentage of the heated paper. This experimental setup is used to investigate the mechanism of paper curl when a temperature difference exists between the two plates. It is found that the temperature gradient lead to moisture transfer from the high temperature side to the low temperature side of the paper. The subsequent evaporation of this moisture gives rise to a higher degree of shrinkage at the low temperature side. Calculations are carried out to predict the amount of paper curl that is expected for temperature differences and the results are found to be in good agreement with experimental observations.