An image forming apparatus includes an image bearer, a toner image forming device, a plurality of image density detectors, and a controller. The plurality of image density detectors are disposed at predetermined intervals opposite the image bearer in a width direction of the image bearer. The controller causes the toner image forming device to form toner image patterns having an identical density at the plurality of positions on the image bearer and the plurality of image density detectors detects a density of the toner image patterns. Based on the detected density of the toner image patterns, the controller identifies multiple cyclic fluctuations of the density of the toner image patterns and adjusts an image forming condition based on the multiple cyclic fluctuations of the density of the toner image patterns to decrease an amplitude caused by the multiple cyclic fluctuations of the density of the toner image patterns.

An image forming apparatus including a control unit configured to execute a first mode and a second mode of forming images on first through third image bearing members. In the first mode, a toner image is formed on a third image bearing member without having toner images formed on first and second image bearing members in a state where the first through third image bearing members are abutted against an intermediate transfer body. In the first mode, the control unit controls at least a first charging device such that a primary transfer contrast in a first primary transfer portion is set equal to or greater than a discharge starting voltage, and applies an AC voltage to a second charging device such that a discharge current having a current quantity smaller than that in the second mode.

A toner includes a crystalline polyester resin and an amorphous polyester resin. A ratio of the storage modulus of the toner G′ (T.sub.O) at a temperature T.sub.O to the storage modulus of the toner G′ (T.sub.O+3) at a temperature T.sub.O+3 is greater than or equal to 10, in a case where the temperature T.sub.O is within a range from 50° C. to 65° C.

An image formation apparatus having a recording medium held between a photosensitive drum and a transfer belt and transferring a toner image from the photosensitive drum to the recording medium includes: a first heating unit to which power is supplied directly from outside when power of the apparatus is off; a second heating unit used in heating control when the power of the apparatus is on; a humidity detection unit configured to detect humidity inside the apparatus; and a control unit configured to, when the power of the apparatus is on, heat the transfer belt by controlling the first heating unit and the second heating unit on the basis of output of the humidity detection unit, wherein the transfer belt is heated by the first heating unit when the power of the apparatus is off.

An image forming apparatus includes a rotatable image bearing member, a rotatable transfer member, a first driving source to drive the image bearing member, a second driving source to drive the transfer member, and a control. Based on a toner amount per unit area of the toner image transferred to each of a plurality of first divided regions of an in-plane of a recording material in a feeding direction, the control portion controls a driving speed of the transfer member while each of the plurality of the first divided regions passes through a transfer portion. The control portion acquires an index value correlating with a toner amount of the toner image transferred to each of a plurality of second divided regions of the first divided region in a widthwise direction, and controls the driving speed based on the index value while the first divided region passes through the transfer portion.

An image forming apparatus includes image forming portions for forming images on a photosensitive member with different color developers by developing rollers. Developing roller moving mechanisms include (i) a developing roller moving member for moving one of the developing roller between a first contacting position contacting an associated photosensitive member and a first separating position separated from the associated photosensitive member and (ii) a first driving force switch for switching between a first transmission state in which a driving force is transmitted to the developing roller moving member to move the developing roller of an image forming portion and a disconnected state in which the transmission of the driving force is disconnected. Driving forces transmitted to the developing roller moving members are supplied from first and second gear trains.

In an image forming apparatus including a power source for forming a secondary-transfer electric field at a secondary-transfer position and for forming a primary-transfer electric field at a primary-transfer position by applying a voltage to a transfer member to pass a current through a constant-voltage element, a potential of an image portion is controlled depending on a detection result of a detecting member.

A transfer device includes: an annular transfer belt including an outer surface, a toner image being transferred to the outer surface of the annular transfer belt; a transfer unit including a transfer cylinder; and a facing roller member that is in contact with an inner surface of the transfer belt, in which the transfer cylinder includes a base material, and a surface layer wound around an outer circumference of the base material, the surface layer being replaceable with respect to the base material, the transfer cylinder has a transfer region where the toner image is transferred from the transfer belt to a recording medium in a state where the recording medium is sandwiched between the transfer cylinder and the outer surface of the transfer belt, the surface layer includes an elastic layer, the surface layer has a thickness of 6.0 mm or more and 10 mm or less and an Asker C hardness of 45° or more and 65° or less, and the facing roller member faces the transfer cylinder in the transfer region.

An image forming apparatus (1) includes photosensitive drums (41y, 41c, 41m, and 41k), static eliminators (45y, 45c, 45m, and 45k), transfer rollers (54y, 54c, 54m, and 54k), a power source (55a) for transfer, and load resistors (47y, 47c, 47m, and 47k). The static eliminators (45y, 45c, and 45m) perform static elimination on adjacently upstream or downstream photosensitive drums (41y, 41c, 41m, and 41k) in a movement direction of a transfer target. The transfer rollers (54y, 54c, 54m, and 54k) are disposed opposite to the respective photosensitive drums (41y, 41c, 41m, and 41k). The power source (55a) for transfer applies potential to the transfer rollers (54y, 54c, 54m, and 54k). The load resistors (57y, 57c, 57m, and 57k) are respectively connected in parallel to one another and in series between the power source (55a) for transfer and the respective transfer rollers (54y, 54c, 54m, and 54k).

Printers comprising a plurality of imaging units are described. In an example, each imaging unit selectively deposits at least one printing substance and an intermediate transfer member cooperates with the imaging units such that, in use of the printer, a printable image may be formed thereon, the printable image comprising printing substance from at least two imaging units.