An image forming apparatus includes an image transfer unit configured to transfer an image formed on an image carrier to a sheet, according to a transfer control parameter, and a transfer control unit. The transfer unit is configured to set the transfer control parameter to a first value when a first portion of the image is being transferred to a first area of the sheet and to a second value when a second portion of the image is being transferred to a second area of the sheet transfers an image formed on an image carrier to a sheet.

An image forming apparatus includes: an image bearing member; a developer carrying member configured to contact with the image bearing member and to be separated from the image bearing member; a control unit for controlling the image bearing member and the developer carrying member; and a contact member disposed in contact with the image bearing member. The control unit is configured to sequentially execute: (1) rotating the image bearing member at a first speed in a separated state; (2) switching the image bearing member and the developer carrying member from the separated state to a contact state in a state in which the image bearing member rotates at the first speed; and (3) rotating the image bearing member by decreasing a rotation speed of the image bearing member from the first speed to a second speed smaller than the first speed in the contact state.

An image forming apparatus includes an image bearing member, a developer bearing member, a fixing unit including a heating member, a rotary member which is heated by the heating member, and a nip area where the rotary member comes into contact with a sheet, and configured to perform fixing by heating a developer image transferred to the sheet and fixing the developer image to the sheet in the nip area, and a control unit configured to execute, while the fixing is not performed, a mode in which the image bearing member is rotated with the developer bearing member being in a separated position and the heating member is controlled such that a temperature of a portion of a surface of the rotary member, after the rotary member passes through the nip area, is maintained higher than the temperature of the portion during the fixing.

An image forming apparatus includes: a density unevenness measurement mode processing portion that, in a density unevenness measurement process, detects density of a density unevenness measurement toner image, which has been formed in a rotational direction of the photoreceptor drum, multiple times in the rotational direction and captures in a memory portion all detected density information associating thereof with rotation phases of the photoreceptor drum; and an image quality adjustment processing portion that, in an image quality adjustment mode, detects density of an image quality adjustment toner image, which has been formed at any position in the rotational direction of the photoreceptor drum, in the rotational direction and corrects detected density information based on density information associated with a rotation phase matching a rotation phase where density of the image quality adjustment toner image has been detected among said all density information having been captured in the memory portion by the density unevenness measurement processing portion.

In an image forming apparatus, a peripheral velocity difference is provided between a peripheral velocity of an intermediate transfer belt and a peripheral velocity of an image bearing member, and when a relative moving distance between the image bearing member and the intermediate transfer belt, which is generated in the transfer nip portion because of the peripheral velocity difference, is taken as a shift amount of the toner image, a lower limit value of the shift amount is set to be at least , preferably half of an average perimeter calculated from a weight-average particle diameter of the toner, which is measured in advance.

An image forming apparatus includes an image carrier, an image carrier driver which rotates the image carrier, a rotation detector which detects rotation of the image carrier, a rotary member in contact with the image carrier, a rotary member driver which rotates the rotary member, a first controller which controls the rotary member driver, and a second controller. The second controller controls the image carrier driver based on an output of the rotation detector and also controls the image carrier driver in a manner which attenuates a fluctuation component at a specific frequency. When the first controller changes a surface velocity of the rotary member, the second controller controls the image carrier driver in a manner that attenuates a fluctuation component at a specific frequency related to the changed surface velocity of the rotary member.

An image forming apparatus includes an image transfer unit configured to transfer an image formed on an image carrier to a sheet, according to a transfer control parameter, and a transfer control unit. The transfer unit is configured to set the transfer control parameter to a first value when a first portion of the image is being transferred to a first area of the sheet and to a second value when a second portion of the image is being transferred to a second area of the sheet transfers an image formed on an image carrier to a sheet.

An image forming apparatus includes an image bearing member, a developer bearing member, a fixing unit including a heating member, a rotary member which is heated by the heating member, and a nip area where the rotary member comes into contact with a sheet, and configured to perform fixing by heating a developer image transferred to the sheet and fixing the developer image to the sheet in the nip area, and a control unit configured to execute, while the fixing is not performed, a mode in which the image bearing member is rotated with the developer bearing member being in a separated position and the heating member is controlled such that a temperature of a portion of a surface of the rotary member, after the rotary member passes through the nip area, is maintained higher than the temperature of the portion during the fixing.

An image-forming apparatus that is capable of accurately detecting skew angle when arriving at a resist roller. In the image-forming apparatus, the resist roller feeds the printing paper to a printing unit at specified timing, and the printing unit performs printing on the printing paper. The flat-conveying section is formed between the paper-supply roller and the resist roller, and conveys the paper in a flat state. The camera takes images of the edge of the front end of the printing paper that is conveyed in the flat-conveying section. The camera-driving apparatus causes the camera to move along the flat-conveying section at the designed conveying speed of the printing paper. The skew-detection unit, based on images taken in the flat-conveying section by the camera, detects the skew angle when arriving at the resist roller as the arrival skew angle.

A reciprocating mechanism reciprocates by drive force from a drive source and to press a chute to move from a first position to a second position. In response to determining that a parameter is greater than a threshold for the parameter, a controller executes a first mode of actuating the drive source when conveying one sheet. The parameter decreases as a conveyance speed of the sheet at the fixing nip increases. The threshold is such a value that, when the parameter is greater than the threshold, a difference between a conveyance speed of the sheet at a transfer nip and the conveyance speed of the sheet at the fixing nip is greater than a particular level. In response to determining that the parameter is smaller than or equal to the threshold, the controller executes a second mode of not actuating the drive source when conveying one sheet.