Abstract: A transfer arrangement is used in a transfer portion of an image forming apparatus. The transfer arrangement includes an electrically conductive member that contacts a toner image bearing member of the image forming apparatus. The electrically conductive member is made of polyurethane resin to which electrically conducive polymer is added. An adding amount of the electrically conductive polymer with respect to the polyurethane resin is from 8 wt % to 40 wt %.

Abstract: A developing device includes a developer supporting member for supporting developer and a developer charging member disposed to face the developer supporting member for charging and supplying the developer to the developer supporting member. The developer supporting member has a surface having a calculated average surface roughness Ra between 0.1 ?m and 0.6 ?m and a surface free energy SFE between 15 mN/m and 26 mN/m. Further, the developer charging member has an Asker F hardness Haf between 24° and 56°.

Abstract: A transfer unit transfers an image formed on an image bearing body (a photoconductive drum or an intermediate transfer belt) onto a medium by an electrostatic force. The transfer unit includes a transfer belt and a transfer roller. The transfer roller extends parallel to the image bearing body and transfers a toner image onto a medium. The transfer roller is pressed toward the image bearing body under a pressing force in a range of 28-112 gf/cm. The transfer belt is held between the transfer roller and the image bearing body in a sandwiched relation to define a transfer point between the transfer belt and the image bearing body. The transfer belt transports the medium through the transfer point.

Abstract: A conductive foamed roller includes a metal shaft portion and a conductive foamed rubber portion. The conductive foamed roller has a permanent compressive strain of equal to or less than 1.75%.

Abstract: A developing agent image is formed by adhering a developing agent onto an electrostatic latent image formed on an image holding material and transferred onto an image forming medium, thereby forming an image. A resistance value ratio of a resistance value of a transfer member arranged so as to face the image holding material when a voltage 1000 V is applied to the transfer member to a resistance value when a voltage 500 V is applied is set to (0.5?ratio?0.89). Likewise, a resistance value ratio of a resistance value when 2000 V is applied to that when 1000 V is applied is set to (0.3?ratio?0.88). Since a just enough transfer current can be optimally generated, image quality can be improved and an image forming apparatus which does not need a large-capacity power source and an elastic roller are provided.

Abstract: A transfer unit transfers an image formed on an image bearing body (a photoconductive drum or an intermediate transfer belt) onto a medium by the electrostatic force. The transfer unit includes a transfer belt and a transfer roller. The transfer roller extends parallel to the image bearing body and transfers a toner image onto a medium. The transfer roller is pressed toward the image bearing body under a pressing force in a range of 28-112 gf/cm. The transport belt is held between the transfer roller and the image bearing body in a sandwiched relation to define a transfer point between the transport belt and the image bearing body. The transport belt transports the medium through the transfer point.

Abstract: A transfer member is used in a transfer portion of an image forming apparatus. The transfer member includes an electrically conductive member that contacts a toner image bearing member of the image forming apparatus. The electrically conductive member is made of polyurethane resin to which electrically conducive polymer is added. An adding amount of the electrically conductive polymer with respect to the polyurethane resin is from 8 wt % to 40 wt %.

Abstract: A developing agent image is formed by adhering a developing agent onto an electrostatic latent image formed on an image holding material and transferred onto an image forming medium, thereby forming an image. A resistance value ratio of a resistance value of a transfer member arranged so as to face the image holding material when a voltage 1000 [V] is applied to the transfer member to a resistance value when a voltage 500 [V] is applied is set to (0.5≦ratio≦0.89). Likewise, a resistance value ratio of a resistance value when 2000 [V] is applied to that when 1000 [V] is applied is set to (0.3≦ratio≦0.88). Since a just enough transfer current can be optimally generated, image quality can be improved and an image forming apparatus which does not need a large-capacity power source and an elastic roller are provided.

Abstract: An electrophotographic printer has neutralizing units and a fixing unit that are disposed in the transport path of a print medium. The neutralizing units neutralize a toner image surface of the print medium entering the fixing unit and a non-printed surface of the print medium exiting the fixing unit. The fixing unit includes two rollers. A fixing roller incorporates a heat source that generates heat for fusing a toner image on the print medium. A pressure roller is in pressure engagement with the fixing roller. At least one of the fixing roller and pressure roller includes a resilient member that covers a metal shaft and an insulation layer that covers the resilient member. The resilient member may contain electrically conductive whiskers that extend radially in three dimensions. The whiskers are dispersed such that a surface of the insulation layer and a surface of the shaft are electrically continuous.

Abstract: An electrophotographic printer has neutralizing units and a fixing unit that are disposed in the transport path of a print medium. The neutralizing units neutralize a toner image surface of the print medium entering the fixing unit and a non-printed surface of the print medium exiting the fixing unit. The fixing unit includes two rollers. A fixing roller incorporates a heat source that generates heat for fusing a toner image on the print medium. A pressure roller is in pressure engagement with the fixing roller. At least one of the fixing roller and pressure roller includes a resilient member that covers a metal shaft and an insulation layer that covers the resilient member. The resilient member may contain electrically conductive whiskers that extend radially in three dimensions. The whiskers are dispersed such that a surface of the insulation layer and a surface of the shaft are electrically continuous.

Abstract: A transfer roller is used in an electrophotographic printer. The transfer roller rotates in contact with a rotating photoconductive drum with a print medium travelling therebetween. The transfer roller has a metal shaft around which a rubber roller is formed. The rubber roller is sponge-like and electrically semiconductive. The rubber roller is covered with a resin tube which has a lower layer formed on the rubber roller and an upper layer formed on the lower layer. One of the upper and lower layers has a higher sealing effect than the other of the upper and lower layers, and the other of the upper and lower layers has a higher stability of electrical resistance than the one of the upper and lower layer.