An image forming apparatus includes a rotatable image bearing member, a charging member, a developing member, a transfer member, an exposure unit, and a controller. The controller executes a preparatory operation in which before an image forming operation, rotation of the image bearing member is started and a charging voltage and a developing voltage are increased stepwise. In the preparatory operation, the controller carries out control so as to start application of the charging voltage at a voltage value not less than a discharge start voltage of the charging member before a surface region of the image bearing member positioned in a developing portion at a time of a start of the rotation of the image bearing member reaches a charging portion in a state which a surface of the image bearing member is exposed to light by the exposure unit.

A control circuit executes voltage adjustment processing of adjusting a voltage output from a transfer power source so that a current detected by a detection circuit becomes a predetermined current value. The voltage adjustment processing is executed before a toner image is transferred from at least one of a first image bearing member and a second image bearing member to an intermediate transfer belt. A processor determines whether the second transfer member is in a state of contact or is in a state of separation on the basis of behavior of the current detected by the detection circuit in a period in which the control circuit is executing the voltage adjustment processing.

An image forming apparatus includes: a sensing portion configured to sense a current that flows through a secondary transfer member, or a voltage that has been applied; and a controller configured to perform an operation to determine a transfer voltage to be applied to the secondary transfer member in secondary transfer, on a basis of a result of sensing performed by the sensing portion at a time when a test voltage has been applied to the secondary transfer member in non-image formation, and the controller performs, in the operation, controlling a first application portion and a second application portion not to apply the voltage to a primary transfer member during a period of applying the test voltage to the secondary transfer member.

An image forming apparatus includes a photosensitive drum, a charging roller, a development device, a transfer roller, a first electricity eliminator and a controller. The photosensitive drum is provided on a conveyance path along which a sheet is conveyed. The charging roller charges the photosensitive drum. The development device develops an electrostatic latent image formed on the photosensitive drum charged by the charging roller. The transfer roller faces the photosensitive drum across the conveyance path and generates a transfer bias. The first electricity eliminator irradiates the photosensitive drum with light on a downstream side of the development device in a rotational direction of the photosensitive drum and on an upstream side of the transfer roller in the rotational direction. The controller which controls the first electricity eliminator so as to irradiate only a non-sheet passing area of the photosensitive drum with the light.

An image forming apparatus includes a change processing portion, a detection processing portion, a second acquisition processing portion, and an adjustment processing portion. The change processing portion changes a transfer current when a plurality of specific toner images which each include a toner layer of C formed on an image-carrying member and a toner layer of M are each transferred to a sheet. The detection processing portion detects a specific image that corresponds to each specific toner image included in the captured image of the sheet. The second acquisition processing portion acquires, for each of detected specific images, a skewness of a histogram of gradation values of a color mixture of M and Y in pixels included in each of the specific images. The adjustment processing portion adjusts the transfer current based on: the skewness acquired for each of the specific images; and the transfer current corresponding to the skewness.

A transfer device includes: a transfer drum that has a groove-like recess extending in an axial direction in an outer circumferential portion thereof, rotates about an axis thereof, and comes into contact with a medium being transported at a portion thereof on an upstream side of the recess in a rotation direction; a nip member, the nip member and the transfer drum forming therebetween a nip part where the medium is nipped; an application member that applies a voltage to the nip part where the medium is nipped, so that an image is transferred to the medium; and a contact mechanism that causes the nip member to come into contact only with a portion on the upstream side of the recess in the transfer drum in the rotation direction at a transfer-start time when the transfer of the image to the medium starts.

A biasing force adjusting device includes a roller, a roller holder, a first biasing member, and a second biasing member. The roller faces a mover. The roller holder holds the roller and is displaceable with respect to the mover. The first biasing member applies a first biasing force to the roller holder to press the roller against the mover. The second biasing member applies a second biasing force greater than the first biasing force to the roller holder to press the roller against the mover.

A transfer device includes a transfer roller and a transfer counter roller. The transfer roller has an elastic layer, contacts with and separates from an image bearer including a belt-shaped elastic body, and nips a recording medium with the image bearer. The transfer counter roller has an elastic layer, is disposed facing the transfer roller, and nips the image bearer with the transfer roller. The transfer counter roller or the transfer roller is applied with a bias to transfer the toner image. Each of the elastic layers of the transfer roller and the transfer counter roller has an Asker C hardness of 75 or less. A difference in thickness between the elastic layers of the transfer roller and the transfer counter roller is ±3% or less.

In a case where a transfer roller is viewed from a direction orthogonal to a rotation axis direction of a shaft, the shaft includes in a longitudinal direction a first contact portion which is provided on an end portion side of an elastic portion and in which the shaft and the elastic portion are in contact with each other and a second contact portion which is provided on a more inner side than the first contact portion and in which the shaft and the elastic portion are in contact with each other. The transfer roller includes a void between the first contact portion and the second contact portion in the longitudinal direction, and the void is arranged at least on a more inner side than an end portion of a transfer material having a maximum size.

A region of an image bearing member that comes into contact with a recording material at a nip in a state in which the recording material is held by the nip is a first region, and a region of the image bearing member that does not come into contact with the recording material at the nip in a state in which the recording material is not held by the nip is a second region. A controller controls to apply a first developing voltage to a developer bearing member when the first region in which a first surface potential has been formed faces a developer bearing member and apply a second developing voltage lower than an absolute value of the first developing voltage to the developer bearing member when the second region in which a second surface potential has been formed faces the developer bearing member.