An exposing unit forms a latent-image electric potential on each photosensitive drum. A detecting toner image of each color is transferred to an intermediate transfer belt using a first potential difference between a latent-image electric potential and the potential of an intermediate transfer belt at each primary transfer portion. When the polarity of voltage to be applied from a transfer power source to a secondary transfer roller is to be switched to an opposite polarity while the detecting toner image of each color is passing through each primary transfer portion, the absolute value of a second potential difference between the potential of the intermediate transfer belt and the background electrical potential of each photosensitive drum is made equal to or greater than the absolute value of the first potential difference by a control unit.

An image forming apparatus includes a first image bearing member, a second image bearing member, an intermediate transfer belt, a first primary transfer member, a second primary transfer member, a secondary transfer outer member, a pre-secondary transfer stretch roller, a driving roller, and an execution portion. The execution portion is configured to execute a first monochromatic mode in which a bias smaller than the primary transfer bias applied to the first primary transfer member in a case where a toner image is formed on the first image bearing member is applied to the first primary transfer member, and the primary transfer bias applied to the second primary transfer member in a case where a toner image is formed on the second image bearing member is applied to the second primary transfer member.

In an image forming apparatus including a plurality of image forming stations, a pre-exposure device is not provided in at least a most upstream image forming station at which a toner image formed by the image forming station cannot arrive, and the pre-exposure device is provided in at least a most downstream image forming station at which the toner image formed by the image forming station can arrive.

An image forming apparatus includes an image bearing member, an intermediary transfer belt, a primary transfer roller provided so that a contact region between the roller and the belt and a contact region between the image bearing member and the belt are in a non-overlapping state with each other with respect to a movement direction of the belt, a primary transfer voltage source, a current detecting portion, an executing portion configured to acquire information on a discharge start voltage on the basis of a detection result of the detecting portion in a period other than a period of primary transfer by applying the voltage to the roller; and a setting portion configured to set, on the basis of an execution result of the executing portion, a primary transfer voltage applied to the roller by the primary transfer voltage source in the period of the primary transfer.

An image forming apparatus transfers toner images of respective colors, formed on photosensitive drums, onto an intermediate transfer belt conveyed in a predetermined direction to thereby form a color toner image. A steering roller tilts the intermediate transfer belt in a direction orthogonal to the conveying direction. A first sensor detects a position of a belt lateral end of the belt, and when controlling driving of the steering roller based on a detection result of the first sensor, a controller performs predetermined filtering on the detection result, to thereby control the driving of the steering roller according to the detection result subjected to the predetermined filtering.

An image forming apparatus includes a transport belt, a first intermediate transfer belt, and a second intermediate transfer belt. The transport belt is disposed along a transport path extending in a vertical direction. The transport belt is configured to transport a recording medium while coming into contact with one surface of the recording medium. The first intermediate transfer belt is configured to sandwich the recording medium together with the transport belt. An image is transferred from the first intermediate transfer belt to the recording medium. The second intermediate transfer belt is disposed above the first intermediate transfer belt. The second intermediate transfer belt is configured to sandwich, together with the transport belt, the recording medium which is in a state where the recording medium is sandwiched between the first intermediate transfer belt and the transport belt. An image being transferred from the second intermediate transfer belt to the recording medium.

A moisture detecting apparatus includes: a light emitting unit including a first light source configured to emit light having a first wavelength as a peak wavelength, and a second light source configured to emit light having a second wavelength as a peak wavelength; a detecting unit configured to detect a first detection value indicating an extent to which the light emitted from the first light source is transmitted through a recording material, and a second detection value indicating an extent to which the light emitted by the second light source is transmitted through the recording material, based on a light receiving result of a light receiving unit; and a determination unit configured to determine a value related to a moisture content of the recording material based on the first detection value and the second detection value.

An image forming apparatus, including: a converting unit configured to convert image data based on a conversion condition; an image forming unit; a measurement unit; and a controller configured to control the image forming unit to form a plurality of measurement images including a first measurement image and a second measurement image, wherein the controller obtains first output characteristics based on a current measurement result of the first measurement image and a previous measurement result of the second measurement image to generate the conversion condition, and wherein the controller obtains second output characteristics based on a current measurement results of the second measurement image and a previous measurement result of the first measurement image to generate the conversion condition.

An image forming apparatus includes an image forming unit configured to form a predetermined pattern image on a sheet, a notifying unit configured to provide a notification of an orientation for placing the sheet on which the predetermined pattern image is formed by the image forming unit, on a placement portion, a reading unit configured to read the sheet on a line to line basis, to generate image data, and a detection unit configured to detect a streak-shaped image extending in a direction along a predetermined edge of the sheet, by analyzing the image data generated by reading the sheet by the reading unit, wherein the notifying unit provides a notification of a placement orientation for allowing the sheet, on which the predetermined pattern image is formed, to be read on a line to line basis, the line extending in a direction along the predetermined edge.

An image forming apparatus includes a transfer belt rotating in a rotational direction, photosensitive drums, primary transferring parts, static eliminating parts and cleaning parts. The static eliminating part is arranged between the primary transferring part and the cleaning part, and includes a light guide body and a light source arranged at one end side of the light guide body. The static eliminating part irradiates upstream and downstream sides from the light guide body in the rotational direction with the static eliminating light. The image forming apparatus comprises a first light shading part and/or a second light shading part. The first/second light shading part is arranged between the photosensitive drum at a downstream/upstream side from the light guide body in the rotational direction and the light guide body to adjust pre-transfer/post-transfer static eliminating light quantity from the light guide body to the downstream/upstream side photosensitive drum.