An image forming apparatus includes a formation target that is wound around rotating bodies including a driving roller and transported by the rotating bodies including the driving roller while forming a shape having linear portions each of which forms a different angle, which is an acute angle or an angle of zero degrees, with a horizontal direction when viewed in an axial direction of the driving roller, first image forming bodies that are arranged along one of the linear portions in such a manner as to be spaced apart from each other by a first distance and that form images onto the formation target, and second image forming bodies that are arranged along another one of the linear portions, the other linear portion forming the angle larger than the angle formed by the one linear portion, in such a manner as to be spaced apart from each other by a second distance shorter than the first distance and that form images onto the formation target.

An image forming apparatus includes a formation target that is wound around rotating bodies including a driving roller and transported by the rotating bodies including the driving roller while forming a shape having linear portions each of which forms a different angle, which is an acute angle or an angle of zero degrees, with a horizontal direction when viewed in an axial direction of the driving roller, first image forming bodies that are arranged along one of the linear portions in such a manner as to be spaced apart from each other by a first distance and that form images onto the formation target, and second image forming bodies that are arranged along another one of the linear portions, the other linear portion forming the angle larger than the angle formed by the one linear portion, in such a manner as to be spaced apart from each other by a second distance shorter than the first distance and that form images onto the formation target.

A fixing device comprising a fixing belt, a rotating member to be in engagement with an outer circumferential surface of the fixing belt, to form a fixing nip between the fixing belt and the rotating member, and sliding members on both ends of the fixing belt.

A fixing device comprising a fixing belt, a rotating member to be in engagement with an outer circumferential surface of the fixing belt, to form a fixing nip between the fixing belt and the rotating member, and sliding members on both ends of the fixing belt.

A fixing device comprising a fixing belt, a rotating member arranged to be in engagement with an outer circumferential surface of the fixing belt, a nip forming member to press the fixing belt, to form a fixing nip between the fixing belt and the rotating member, and sliding members on both ends of the fixing belt and to rotate together with the fixing belt.

An image forming apparatus includes an image forming target looped around plural rotators including a driving roller, having at least one straight portion that is shaped straight when viewed in an axial direction of the driving roller, and transported by the driving roller and the rotators, and three or more image formers arranged along the straight portion and configured to form images on the image forming target. An adjacency distance along the straight portion between the image formers adjacent to each other on the straight portion is an integral multiple of an outer peripheral length of the driving roller. The adjacency distance at a downstream end is shorter than the adjacency distance at an upstream end, and one of the adjacency distances is equal to or shorter than the adjacency distance that is relatively on an upstream side.

A fixing device comprising a fixing belt, a rotating member arranged to be in engagement with an outer circumferential surface of the fixing belt, a nip forming member to press the fixing belt, to form a fixing nip between the fixing belt and the rotating member, and sliding members on both ends of the fixing belt and to rotate together with the fixing belt.

A single-layer electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The conductive substrate contains aluminum or an aluminum alloy. A surface of the conductive substrate has an aluminum oxide film or an aluminum alloy oxide film. The photosensitive layer is disposed directly on the conductive substrate. The photosensitive layer contains an electron transport material. The electron transport material has a reduction potential of at least 0.88 V and no greater than 0.66 V versus a reference electrode (Ag/Ag.sup.+). The single-layer electrophotographic photosensitive member has a leakage onset voltage of at least 5.0 kV in a high temperature and humidity environment at a temperature of 30 C. and a relative humidity of 80%. The leakage onset voltage is a voltage applied to the single-layer electrophotographic photosensitive member at which current leakage starts.

A fixing device including fixing belt, a heat source to heat the fixing belt, a rotating member in engagement with an outer circumferential surface of the fixing belt, a nip forming member to pressurize the fixing belt, thereby forming a fixing nip between the fixing belt and the rotating member, and sliding members on both ends of the fixing belt and rotated together with the fixing belt. A rotation center of each of the sliding members is on an upstream side compared to a rotation center of the rotating member along a feeding direction of a printing medium, and a shortest distance between a tangential line of an outer circumferential surface of each of the sliding members and the rotation center of the rotating member is equal to or greater than a shortest distance between the fixing nip and the rotation center of the rotating member.

A toner density sensor includes: a light emitting element configured to radiate light; a light receiving element configured to receive the light emitted from the light emitting element and reflected from a detection object; a substrate whereon the light emitting element and the light receiving element are surface mounted; a case covering the light emitting element and the light receiving element; an optical path configured parallel to the substrate for light generated from the light emitting element; a groove provided in the substrate from the end part of the substrate in the direction light travels from the light emitting element to between the light emitting element and the light receiving element, the groove recessed from the mounting surface in the thickness direction of the substrate; and an insert provided to the case and configured for insertion into the groove.