The belt conveyance device includes a plurality of rollers, a belt, a meandering correction part, and an adjustment part. The rollers are disposed at intervals each other and rotate around axes. The belt is disposed around the plurality of rollers and travels. The meandering correction part shifts one end portion in an axial direction of a tension roller included in the plurality of rollers in a radial direction within a predetermined range to correct a meandering of the belt. The adjustment part shifts the other end portion in the axial direction of the tension roller in the radial direction such that a position of the one end portion of the tension roller is variable under a state where the meandering of the belt is corrected.

An image forming apparatus includes a developer that forms a toner image on an endless belt that is suspended over outer portions of a plurality of rollers, a driver that rotates at least one driving roller out of the plurality of rollers, a position adjustment mechanism that corrects relative positions of the plurality of rollers relative to one another, and a hardware processor, wherein the hardware processor controls the position adjustment mechanism to correct a relative position between the belt and the driving roller with tension applied to the belt being a second tension smaller than a first tension that is applied in a developing state in which a toner image is formed on the belt by the developer.

An image forming apparatus 100 employs a constitution in which in a case that a relative position between an inner roller 32 and an outer member 41 with respect to a circumferential direction of the inner roller 32 is changed in a period after a preceding recording material S passes through a transfer portion N2 and until a recording material S subsequent to the preceding recording material S reaches the transfer portion N2 during execution of a job for forming and outputting images on a plurality of recording materials S, a controller 150 controls a position changing mechanism 1 and a contact and separation mechanism 2 so that a separating operation for separating the outer roller 41 from the belt 31 and then the above-described relative position is changed.

An electrophotographic belt including at least a base layer and a surface layer on or above the base layer, the surface layer including a binder resin and perfluoropolyether (PFPE), having a thickness of 2 μm or more. PFPE is removed to obtain a PFPE-removed surface layer, the PFPE-removed surface layer has pores having openings at an outer surface thereof. When assuming that the PFPE-removed surface layer is a solid-surface layer, a ratio of a total volume of the pores contained in the PFPE-removed surface layer to a volume of the solid-surface layer is 8 to 25%. A ratio of a sum of areas of the openings to a unit area (1 μm.sup.2) of the outer surface of the PFPE-removed surface layer is 10 to 35%, and the number of the openings per unit area (1 μm.sup.2) of the outer surface of the PFPE-removed surface layer is 10 to 500.

An image forming apparatus includes an image bearing member that bears a toner image, a transfer unit having an endless belt, a positioning unit that positions the transfer unit, and a secondary transfer member. The secondary transfer member is in touch with the endless belt to form a secondary transfer portion. When the toner image is transferred to the endless belt from the image bearing member, the secondary transfer member transfers the toner image from the endless belt at the secondary transfer portion to a transfer material. The positioning unit includes a first abutting face to position the transfer unit in a conveyance direction and a second abutting face to position the transfer unit in a direction opposite to the conveyance direction. An attaching/detaching direction of the transfer unit is a direction intersecting with a surface of the transfer material to which the toner image is transferred.

An image forming apparatus includes: an annular transfer belt to which an image is transferred; a transfer roller that transfers an image to a recording medium when the recording medium passes through a transfer area formed between the transfer roller and the transfer belt; a drive mechanism that causes the transfer roller to rotate; and a speed adjustment mechanism that adjusts a rotational speed of the transfer roller achieved by the drive mechanism in units of a cycle of the transfer roller, and switches between a first adjustment pattern and a second adjustment pattern to execute switched adjustment pattern in a cycle including a state in which the transfer roller transports the recording medium, the first adjustment pattern for adjusting the rotational speed of the transfer roller, the second adjustment pattern for adjusting the rotational speed of the transfer roller with a pattern different from the first adjustment pattern.

A transfer device includes a transfer roller and a transfer counter roller. The transfer roller has an elastic layer, contacts with and separates from an image bearer including a belt-shaped elastic body, and nips a recording medium with the image bearer. The transfer counter roller has an elastic layer, is disposed facing the transfer roller, and nips the image bearer with the transfer roller. The transfer counter roller or the transfer roller is applied with a bias to transfer the toner image. Each of the elastic layers of the transfer roller and the transfer counter roller has an Asker C hardness of 75 or less. A difference in thickness between the elastic layers of the transfer roller and the transfer counter roller is ±3% or less.

An electrophotographic belt includes a biaxially stretched cylindrical film as a base layer, wherein the biaxially stretched cylindrical film includes crystalline polyester, amorphous polyester and carbon black, a content of the carbon black with respect to the biaxially stretched cylindrical film is 2.0% by mass or more, and a surface resistivity measured on the surface of the biaxially stretched cylindrical film in an environment of 23° C. and 50% RH is 1×10.sup.3 Ω/square or higher and 1×10.sup.13 Ω/square or lower, and A/B is 3.00 or smaller, where A (Q/square) represents a surface resistivity of the biaxially stretched cylindrical film after the film is left to stand for 24 hours in an environment of 23° C. and 50% RH, and B (Ω/square) represents a surface resistivity of the biaxially stretched cylindrical film after the film is left to stand for 24 hours in an environment of 30° C. and 80% RH.

An endless belt includes a polyamide imide resin layer in which a content of at least one solvent selected from a solvent group A consisting of a urea solvent, an alkoxy group-containing amide solvent, and an ester group-containing amide solvent is from 0.005 parts by weight to 3 parts by weight with respect to 100 parts by weight of the polyamide imide resin layer.

A relationship 150≦Rs (Ω)/Rm (Ω)≦4000 is established in an environment of a temperature of 15° C. and a humidity of 10% in a case where a surface resistance of a transfer roller is Rs (Ω) when a current is fed between a pair of electrodes facing each other in an axial direction of the transfer roller and arranged on a surface of the transfer roller with an interval of 5 mm therebetween, the electrodes having a width of 20 mm in a circumferential direction of the transfer roller in a state of being arranged on the transfer roller, and in a case where a combined resistance of a first layer and a second layer is Rm (Ω) when the current is fed from a core portion to an outer peripheral surface of the second layer.