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.

An image forming apparatus includes an image carrier that carries an image, a transfer body that transports a recording medium in a contact region between the image carrier and the transfer body, a pair of transport members that are disposed upstream of the contact region in a transport direction, and transport the recording medium to the contact region, a guide member that includes, between the contact region and the pair of transport members, a portion on a downstream side in the transport direction which serves as a free end portion and a portion on an upstream side in the transport direction which is supported in a cantilever state, that guides a non-transfer surface of the recording medium, that is elastically deformed, and that has a cutout, and a detection unit that detects an image on an outer peripheral surface of the image carrier on a optical path.

An image forming device includes a plurality of image formation units each configured to form an image of one of a plurality of colors, and a patch image transfer unit configured to control transfer conditions during transferring a patch group that is a pattern for detecting a position shift and formed on an intermediate transfer belt onto a secondary transfer belt. The patch image transfer unit is configured to transfer patches of at least single color for which a band of transfer efficiency is narrowest, of the patch group, onto the secondary transfer belt under transfer conditions for the color, and during transition to the transfer conditions for the color from other transfer conditions or during transition from the transfer conditions for the color to the other transfer conditions, patches of a color other than the color, of the patch group is transferred onto the secondary transfer belt.

An image forming apparatus includes an image carrier, a transfer body, a pair of transport members, and first and second guide members. The first and second guide members each have an upstream portion with respect to the transport direction that is cantilevered between the contact area of the transfer body and the image carrier, and the transport members. The first guide member guides the non-transfer surface of plain paper such that the plain paper contacts the image carrier upstream of the contact area with respect to the transport direction, and guides the non-transfer surface of heavy paper while being pressed by the non-transfer surface and elastically deformed to the transfer body side. The second guide member guides the transfer surface of plain paper while being elastically deformed to the image carrier side, and guides the transfer surface of heavy paper while being elastically returned to the transfer body side.

An image forming apparatus includes a photoconductor, a charger that charges the photoconductor, a transfer unit that transfers a toner image formed on the photoconductor to a transfer device, a charging power supply that outputs AC voltage for applying a charging bias to the charger, a transfer power supply that outputs DC voltage or DC current for applying a transfer bias to the transfer unit, an output detector that detects an output value of the DC voltage or the DC current, and a controller that calculates load impedance of the photoconductor based on the detected output value of the DC voltage or DC current detected by the output detector while modifying the output of the AC voltage by the charging power supply and sets the output of the AC voltage that the load impedance starts converging into a predetermined value as an adjusted AC output to the charging power supply.

An image forming apparatus includes an image forming portion, an image input portion, a transfer unit, a transfer voltage power supply, and a control portion. The transfer unit includes a transfer roller having a metal shaft and an elastic layer laid around the outer circumferential face of the metal shaft to form a transfer nip by keeping the elastic layer in pressed contact with an image carrying member, and transfers a toner image formed on the image carrying member to a recording medium as it passes through the transfer nip. The transfer unit includes, as the transfer roller, a first roller, and a second roller having a larger axial-size elastic layer compared to the first roller. The control portion arranges first or second roller opposite the image carrying member according to width-direction sizes of the recording medium and the image data fed to the image input portion.

An image forming apparatus includes an image bearing member, a transfer rotating body, a feeding means and a control means that controls a feeding speed of a recording material in a feeding portion at the feeding means. Wherein a first timing is a timing during when a rear end of the recording material with respect to a feeding direction passes through a transferring portion and a second timing is a timing when the rear end of the recording material is separated from the image bearing member after passing through the transferring portion, the control means can control the feeding means for one recording material so that a feeding speed of the recording material at the second timing in the feeding portion becomes faster than that of at the first timing in the feeding portion.

An image forming apparatus includes image bearing members, an intermediary transfer member having ion conductivity, primary transfer members, a first voltage applying portion, a secondary transfer member, a second voltage applying portion, and a controller. On the basis of image information, the controller controls a transfer voltage applied to the secondary transfer member so as to be different between a first voltage when a first region in which a coverage indicating a ratio occupied by an image region per predetermined area is a first coverage passes through the secondary transfer portion and a second voltage when a second region in which the coverage is a second coverage larger than the first coverage passes through the secondary transfer portion. The controller controls a change amount of the first voltage with respect to the second voltage so as to be different between a first mode and a second mode.

When a first roller is in an operation state, a driving device displaces a second displacement member in a first direction. This displaces a second locking portion of a slide portion to a position to lock a first projection portion of a first roller support member and a second projection portion of a second roller support member, while a first displacement member is held at a first position. The driving device further displaces the second displacement member in a second direction and stops the second displacement member. This allows the first displacement member to be displaced from the first position to a second position, and the second displacement member is further displaced and stopped at a position where the second projection portion is inserted in the recessed portion of the slide portion. This allows a second roller to enter an operation state.

An image forming apparatus includes a first image forming portion, a second image forming portion, a belt, a charging voltage applying portion, and a transfer voltage applying portion. With respect to a movement direction of the recording material, the first image forming portion is provided upstream of the second image forming portion. In an image forming operation, a potential difference between the first transfer voltage and a potential, at the first transfer portion, which is formed on the first image bearing member and does not form the image is larger than a potential difference between the second transfer voltage and a potential, at the second transfer portion, which is formed on the second image bearing member and does not form the image.