An intermediate transfer member including a base layer, wherein the base layer contains a thermoplastic resin and an electroconductive filler dispersed in the thermoplastic resin, and wherein the base layer has a volume resistivity of 1?10.sup.6 to 1?10.sup.13 ?.Math.cm, and the base layer has an electroconductive path index of 0.20 or less.

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.

An image forming apparatus includes an image bearing member, a rotatable endless intermediary transfer belt, an inner roller, an outer roller, a power source, a detecting portion, and a controller. On the basis of a result of detection by the detecting portion when a voltage is applied to the inner roller so as to form a chart on a recording material of a predetermined kind in an operation in an adjusting mode, the controller determines whether a transfer voltage when a toner image is transferred onto the recording material of the predetermined kind is subjected to constant-voltage control so that the voltage applied to the inner roller by the power source becomes a target value or is subjected to constant-current control so that a current supplied to the inner roller becomes a target value.

An image forming apparatus in an embodiment includes an image carrying body, a transfer body, a first mechanism, a sensor, and a second mechanism. The image carrying body carries an image of a developer. The image of the developer is transferred onto the transfer body from the image carrying body. The first mechanism separates the transfer body from the image carrying body. The sensor detects a state of the surface of the transfer body. The second mechanism separates the sensor from the transfer body in association with the first mechanism.

An image forming apparatus in an embodiment includes an image carrying body, a transfer body, a first mechanism, a sensor, and a second mechanism. The image carrying body carries an image of a developer. The image of the developer is transferred onto the transfer body from the image carrying body. The first mechanism separates the transfer body from the image carrying body. The sensor detects a state of the surface of the transfer body. The second mechanism separates the sensor from the transfer body in association with the first mechanism.

An image forming apparatus has a plurality of image forming portions, an intermediate transfer belt having an elastic layer, a plurality of primary transfer members, a contact-separation mechanism, a secondary transfer member, a driving device, a voltage applying device, and a control portion. The contact-separation mechanism is switchable between an all-color pressure state where the primary transfer members are all in pressed contact with the image carrying members via the intermediate transfer belt and an all-color apart state where the primary transfer members are all away from the intermediate transfer belt. At first power-on, the control portion starts driving the image carrying members and the intermediate transfer belt in the all-color apart state, then transits to the all-color pressure state, and then ejects toner from the developing device to the image carrying members to reduce the surface friction coefficient on the image carrying members and the intermediate transfer belt.

A toner image is formed on an intermediate transfer belt using a toner containing a crystalline polyester, and a recording material is interposed between the intermediate transfer belt and a secondary transfer roller having a first layer serving as a surface layer, a second layer formed of a solid layer provided on an inner peripheral side of the first layer, and a third layer formed of a porous elastic layer provided on an inner peripheral side of the second layer, and the toner image is transferred onto the recording material by the secondary transfer roller.

An image forming apparatus includes: a drum unit including a photosensitive drum; a belt unit; and a secondary transfer member. The belt unit includes: a first roller; a second roller spaced apart from the first roller; an intermediate transfer belt supported by the first roller and the second roller; and a primary transfer member. The intermediate transfer belt includes: a first portion; and a second portion. The first portion has an upstream end and a downstream end in a first direction. The second portion has an upstream end and a downstream end in a second direction. The primary transfer member is configured to transfer a toner image from the photosensitive drum to the first portion. The secondary transfer member is capable of contacting the downstream end of the second portion, and is configured to transfer the toner image from the intermediate transfer belt to a sheet.

A belt driving device includes: a belt; and a drive roll and driven rolls that rotate the belt wound around the rolls. As part of the driven rolls, a first driven roll and a second driven roll with a same roll diameter, each having a greatest exceeding eccentricity section or insufficient eccentricity section in a mutual common area are disposed in a non-displaced state in that order at positions with an interval in a rotational direction of the belt, and are driven to rotate so that greatest exceeding eccentricity sections or insufficient eccentricity sections each being the greatest exceeding eccentricity section or insufficient eccentricity section are in opposite phase at central positions in the rotational direction of contact portions of the belt with the first driven roll and the second driven roll.

An intermediate transfer belt includes a surface layer with a solid lubricant added therein on an outer peripheral surface side in abutment with a photosensitive drum and a cleaning blade in a thickness direction. Further, the surface layer includes a plurality of grooves formed along a movement direction of the intermediate transfer belt in a width direction of the intermediate transfer belt. The intermediate transfer belt including the grooves satisfies J(1/K)L(Q/.sub.P)/((Q/.sub.P)+(100/.sub.A))<240.