| 摘要 |
PURPOSE: To suppress the increase in vibration sound and generation of image defects due to change with time in the hardness of an electrostatic charging member having a specific conductive elastic layer and a surface layer in contact with a body to be electrostatically charged by using this electrostatic charged member. CONSTITUTION: The contact type electrostatic charging member is provided with the conductive elastic layer 2b consisting of a foamed body having an expansion rate of at least 10 to 98% and the surface layer 2d to be in contact with the body to be electrostatically charged on the outer side of this elastic layer 2b. The volume resistivity of the conductive elastic layer 2b is specified to 10<2> to 10<10>Ωcm, the JISA hardness to <=50 deg., the compression permanent set rate to <=40% and the surface roughness to <=100μm. In such a case, any voltages, such as DC voltage, superposed voltage of the DC voltage and AC voltage and vibration voltage, are usable as the voltage to be impressed on the electrostatic charging member. Any materials are usable as the conductive elastic layer 2b, insofar as the volume resistivity of these materials is 10<2> to 10<10>Ωcm, the JISA hardness <=50 deg., the compression permanent set rate <=40% and the surface roughness <=100μm.
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