An image forming device continuously forming an image according to a job in a conveying direction of along continuous paper includes: an image formation section forming the image according to the job on the continuous paper; an interval setting section setting a job interval of the image according to the job, which is continuously formed by the image formation section, on the basis of an operation from a user; an image forming process switching section switching two states of a state where the image formation section forms a color image and a state where the image formation section forms a monochromic image; and a switching determination section determining whether or not the two states are switched on the basis of a comparison result between the job interval set by the interval setting section and a paper conveying distance according to a switching time required for switching the two states.

If an inputted job requires switching from a single-color mode to a multicolor mode, an image forming apparatus switches from the single-color mode to the multicolor mode during a relatively long processing waiting time out of processing waiting times between preceding pages and succeeding pages, before a page in the job for forming a multicolor image.

An image forming apparatus, having process units, a transfer unit, a motor, first through fourth cams, a color-linkage gear train, a monochrome-transmission gear train, and a color-transmission gear train, is provided. Each of the process units has a developing unit including a developing roller and a drum unit including a photosensitive drum. The color-linkage gear train rotates the first cam, the second cam, and the third cam in shifted phases. The monochrome-transmission gear train transmits a driving force from the motor to a monochrome clutch, which engages and disengages transmission of the driving force from the monochrome-transmission gear train to the fourth cam. The color-transmission gear train transmits the driving force from the motor to a color clutch, which engages and disengages transmission of the driving force from the color-transmission gear train to the color-linkage gear train.

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.

A positional relationship between a photosensitive drum and an intermediate transfer belt during a period from the start of the driving of the photosensitive drum to the start of image formation, or during a period of the end of the image formation to the stop of the driving of the photosensitive drum enters a separating state in a case where the image formation is executed when the process speed is a first speed, and enters a contacting state in a case where the image formation is executed when the process speed is a second speed.

An image forming apparatus includes an image forming unit, a transfer unit, and a controller. The transfer unit transfers a developer image formed by the image forming unit onto a transfer object. The controller controls each of the image forming unit and the transfer unit on a basis of printing data. The controller performs a printing control to cause a first printing operation and a second printing operation to be executed. The first printing operation forms a first developer image directed to an entire pixel region of a print image and transfers the first developer image onto the transfer object. The second printing operation forms a second developer image directed selectively to a high-gradation pixel region and transfers the second developer image onto the transfer object. The high-gradation pixel region is a pixel region, having a gradation value equal to or greater than a threshold, of the print image.

An image forming apparatus includes an image forming part, a canceling processing part, a first switching processing part and a second switching processing part. The canceling processing part is performable an image canceling operation where a toner image formed on an intermediate transferring member is removed from the intermediate transferring member without transferred to a sheet. The first switching processing part is capable of switching a printing mode in the image forming part between a plurality of printing modes having different printing conditions in the image forming part, based on an image data under waiting for printing and a predetermined first switching condition. The second switching processing part is capable of switching the printing mode based on the image data under waiting for printing and a predetermined second switching condition when the image canceling operation is performed.

An image forming apparatus fixes a toner image onto a sheet by a fixer, and includes: a re-feeding path that normally conveys the sheet having passed through the fixer and guides the sheet toward the fixer; and a hardware processor that switches between first control to discharge the sheet having passed through the fixer toward a discharge destination and second control to re-feed the sheet having passed through the fixer to the fixer through the re-feeding path, depending on a type of an image which is a source of formation of the toner image.

An imaging system includes an endless belt, a tensioning system that applies tension to the endless belt, a contact member that engages with the endless belt, and a detector that detects slack at a part of the endless belt. A controller causes the contact member to be separated from the endless belt so that the tensioning system reduces the slack of the endless belt in response to the detector detecting the slack.

An image forming apparatus includes an intermediate transfer belt, a plurality of rollers including an inner roller and where the intermediate transfer belt is stretched, an outer roller provided at a position facing the inner roller with the intermediate transfer belt in between, and an arm member. The intermediate transfer belt receives transfer of a toner image. The outer roller forms a transfer nip to transfer the toner image from the intermediate transfer belt to a recording medium. The arm member rotatably supports both end parts of the inner roller. When the inner roller is positioned at a first rotating position, the transfer nip is formed at a first position in an outer roller circumferential direction, and when the inner roller is positioned at a second rotating position, the transfer nip is formed at a second position different from the first transfer nip position in the outer roller circumferential direction.