Transfer device, image forming apparatus and method for evaluating electric property

A transfer device comprising:

• an intermediate transfer medium which rotates while contacting an image bearing member;
• and
• a first transfer member which transfers a toner image on the image bearing member to a side of the intermediate transfer medium at a first transfer nip while contacting a backside of the intermediate transfer medium and applying a first transfer bias thereto,
• wherein a first combination of the intermediate transfer medium and the first transfer member has a property such that when the first combination is repeatedly subjected to charging and discharging, in which a voltage of 1 kV with a polarity opposite to a charge of the toner is applied for 60 seconds, and then discharging is performed for 10 seconds, 300 times while measuring a combined volume resistance of the first combination, an absolute value of logarithmic difference between a first combined volume resistance and a 300th combined volume resistance is not greater than 0.8 [log(Ω)].

A transfer device comprising:

• an intermediate transfer medium which rotates while bearing a toner image thereon;
• a transfer member configured to transfer the toner image on the intermediate transfer medium to a receiving material at a transfer nip while contacting a backside of the intermediate transfer medium and applying a negative transfer bias thereto;
• and
• an opposing member which contacts a backside of the receiving material to transfer the toner image on the intermediate transfer medium to the receiving material at the transfer nip together with the transfer member,
• wherein a combination of the intermediate transfer medium and the transfer member has a property such that when the combination is repeatedly subjected to charging and discharging, in which a voltage of −1 kV is applied for 60 seconds, and then discharging is performed for 10 seconds, 300 times while measuring a combined volume resistance of the combination, an absolute value of logarithmic difference between a first combined volume resistance and a 300th combined volume resistance is not greater than 0.5 [log(Ω)].

A method of producing a transfer device of good quality, which includes an intermediate transfer medium and at least one transfer member for applying a transfer bias to the intermediate transfer medium, comprising:

• a) providing a candidate combination of a candidate for the intermediate transfer medium and a candidate for the transfer member;
• b) repeatedly subjecting the candidate combination to a voltage ON-OFF operation, in which a voltage equal to the transfer bias is applied to the combination, predetermined times while measuring a combined volume resistance of the combination;
• c) calculating change of the combined volume resistance of the candidate combination to determine whether the change falls in a predetermined range;
• if the change falls in the predetermined range, the candidate combination is determined to be an acceptable combination;
• if the change does not fall in the predetermined range, providing at least one further candidate combination,
• and repeating the steps b) and c) for the at least one further candidate combination until an acceptable combination has been determined;
• and
• assembling the transfer device using the acceptable combination.