An endless belt includes a polyimide 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 50 ppm to 2,000 ppm.

A belt conveyance apparatus includes a plurality of support rollers, an endless belt, a regulation portion configured to regulate a shift of the endless belt in a width direction, a regulation receiving member configured to contact the regulation portion to receive a regulation force by the regulation portion, and support members disposed on an upstream side, in a conveyance direction of the endless belt, of the support rollers provided with the regulation portion to oppose each other on an inner peripheral surface side and an outer peripheral surface side of the end portion side of the endless belt in the width direction, and configured to regulate a position of the regulation receiving member when the regulation receiving member enters a contact portion with the regulation portion.

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 belt unit, for use in an image forming apparatus, includes an endless belt that moves in a movement direction, a transfer member, a collecting member, a storage container, and a conveyance member. The conveyance member conveys toner in a conveyance direction, rotates about a rotational axis extending in a rotational axis direction, includes a shaft and a conveyance portion provided on a shaft outer surface, and has a helical shape having a helical axis extending in the rotational axis direction. The conveyance member further includes a protruding portion protruding from the shaft outer surface in a direction crossing the conveyance member rotational axis, which has a shape different from the helical shape, and which is provided on a shaft portion downstream of the conveyance portion in the conveyance direction. The rotational axis direction is a direction crossing both the endless belt movement direction and a transfer member longitudinal direction.

The crystallinity of a thermoplastic resin is 8% or more and 25% or less, the average primary particle size of carbon black is 10 nm or more and 30 nm or less, the content of the carbon black is 15.0 parts by mass or more and 30.0 parts by mass or less with respect to 100 parts by mass of an intermediate transfer belt, and (Li+Lo+Lc)/3≤100 nm, where Li, Lo, and Lc are values of an L-function indicating a dispersibility of the carbon black with respect to the thermoplastic resin in an inner peripheral surface region of the intermediate transfer belt, in an outer peripheral surface region, and in a central region that is a central portion of the intermediate transfer belt in a thickness direction of the intermediate transfer belt, respectively.

A polyimide resin film includes: a first layer that contains an imide resin, a bond composition ratio of a sum of a C—N bond and a C—O bond to bonds of all C elements that are present in a surface of the first layer being 4 atm % or more; and a second layer that is provided on the surface of the first layer.

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.

The image forming apparatus includes a control unit configured to selectively execute an operation for applying a voltage with a polarity opposite to an original charging polarity of a toner to a first charging member and a second charging member and an operation for applying a voltage with the polarity opposite to the original charging polarity of the toner to one of the first charging member and the second charging member and a voltage with the same polarity as the original charging polarity of the toner to another of the first charging member and the second charging member as a cleaning operation for charging a secondary transfer residual toner to the polarity opposite to the original charging polarity of the toner by using the first charging member and the second charging member to transfer the secondary transfer residual toner onto an image bearing member.

An image forming apparatus includes a plurality of image bearers, a transfer bias member, and a power source. When the transfer bias member transfers a color toner image onto a recording sheet, a second peak value of a peak-to-peak of a transfer bias, which is smaller than a first peak value of the peak-to-peak in an electrostatic force to move toner from the image bearers or an intermediate transfer body to the recording sheet, is zero or has a first polarity to generate the electrostatic force in a transfer direction to move toner from the image bearers or the intermediate transfer body to the recording sheet. When the transfer bias member transfers a monochromatic toner image including only black toner onto the recording sheet, the second peak value is zero or has a second polarity to generate an electrostatic force in an opposite direction to the transfer direction.

A tension applying device that applies tension to a strip-shaped body supported on a support member, the tension applying device is provided with a moving body that supports the support member, a holding body movably supporting the moving body in a direction in which the tension is applied to the strip-shaped body, a tension spring exerting the tension to the strip-shaped body, a first spring support portion disposed in the holding body and supporting one end of the tension spring, a second spring support portion disposed in the moving body in order to support the other end of the tension spring and disposed on an upstream side from the first spring support portion in the direction in which the tension is applied, and an opening formed in the holding body and in a position corresponding to the second spring support portion.