In an image forming apparatus, when a first sheet and a second sheet are subjected to printing and the second sheet is being conveyed at a particular timing after a sheet sensor detected passage of a trailing end of the first sheet, and when a sheet interval between the first sheet and the second sheet is equal to or greater than a particular threshold interval, a controller positions first and second developing rollers to first and second separated positions, respectively, after developing of images to be transferred onto the first sheet has been completed, positions the developing rollers to be used for printing on the second sheet to respective contact positions, and starts developing images to be transferred on the second sheet. The controller is further configured to perform a color printing using both the first and second developing rollers, and a monochromatic printing using only the second developing roller.

An image forming apparatus, having first, second, third, and fourth photosensitive drums, first, second, third, and fourth developing rollers, a development-driving gear, a development motor, a first development gear train having a first gear, a second development-gear train having a second gear, a process-driving gear, a process motor, a first process-gear train having a third gear, and a second process gear-train having a fourth gear, is provided. The first development-gear train transmits a driving force from the development motor to the first and second developing rollers. The second development-gear train transmits the driving force from the development motor to the third and fourth developing rollers. The first process-gear train transmits a driving force from the process motor to the first and second photosensitive drums. The second process-gear train transmits the driving force from the process motor to the third and fourth photosensitive drums.

An image forming apparatus, having a first photosensitive drum, a second photosensitive drum, a first developing roller, a second developing roller, a first moving mechanism, a second moving mechanism, a driving gear, a motor, a first gear train, a second gear train, and a third gear train, is provided. The first gear train having a first gear transmits a driving force from the motor to the first developing roller. The second gear train having a second gear transmits the driving force from the motor to the second developing roller. The second gear train is provided separately from the first gear train. The third gear train having a third gear transmits the driving force from the motor to at least one of the first moving mechanism and the second moving mechanism. The third gear train is provided separately from the first gear train and the second gear train.

In an image forming apparatus, a first photosensitive drum is disposed upstream of a second photosensitive drum in a conveyance direction. Each of first and second developing rollers is movable between a contact position contacting a corresponding photosensitive drum and a separated position separated from the corresponding photosensitive drum. In a first case where a color print process is executed, a first moving mechanism starts moving the first developing roller toward the contact position, a manual feed roller starts picking up the sheet on a manual feed tray, and a second moving mechanism starts moving the second developing roller toward the contact position. In a second case where the monochrome print process is executed, the manual feed roller starts picking up the sheet on the manual feed tray, and the second moving mechanism starts moving the second developing roller toward the contact position.

An image forming device which forms an image for color correction in the margin of a continuous recording medium such as continuous paper as appropriate without causing erroneous detection by a mark sensor at a post-processing stage. In the image forming device, a printing data generator (control section) performs: acquiring a detection criterion to detect a post-processing image for use at the post-processing stage; creating a color correction image to be used for color correction of an original image according to the detection criterion; and arranging the color correction image as an outer area image in an area other than an original image formation area in printing data.

A controller is configured to, when forming an image on one sheet, in a case where a length of one sheet in a conveyance direction is larger than a first length, drive a moving mechanism to move a plurality of developing rollers from a separation position to a contact position, temporarily stop driving of the moving mechanism, and then, at a first timing, again drive the moving mechanism to move the plurality of developing rollers from the contact position to the separation position; and in a case where the length of the one sheet in the conveyance direction is smaller than or equal to the first length, drive the moving mechanism to move the plurality of developing rollers from the separation position to the contact position and then to move the plurality of developing rollers from the contact position to the separation position without stopping driving of the moving mechanism.

An image forming apparatus includes: a medium transport path; a first image transport path that is disposed so as to oppose the medium transport path and along which an image to be formed on the medium is transported; an image forming part that forms the image and is disposed adjacent to the first image transport path; and a second image transport path that is disposed so as to oppose the medium transport path, that is located at a distance from the image forming part, and along which an image to be formed on the medium is transported, the second image transport path, the first image transport path, and the medium transport path, together surrounding the image forming part.

A stereoscopic image forming method forms a color stereoscopic image on a recording medium having a thermal expansion property. The stereoscopic image forming method includes the steps of: fixing a color image on the thermally expandable recording medium using a color material; and irradiating the fixed color image with light of a light source having a maximum emission wavelength in a wavelength range of 280 to 780 nm. This light is absorbed by a compound contained in the color material to generate heat of the compound.

A high-voltage electrical circuit board is located in a first region that is a region at one side of photosensitive drums in a first direction and outside of the photosensitive drums in the first direction. A first motor drives a conveyance mechanism. A second motor is located in a second region and drives each photosensitive drum. A third motor is located in the second region and drives each developing roller to rotate and to drive a separation mechanism configured to individually move the developing rollers between a contact position and a separation position. A control board is located in the second region. The control board includes a controller configured to control a first applying circuit, the first motor, the second motor, and the third motor. The first motor, the second motor, the third motor, and the control board are located at different positions from one another in the second region.

An image forming apparatus includes a plurality of photosensitive members; a scanner unit including light sources, a rotatable polygonal mirror, and reflecting members; and a fixing portion. Parts of the laser beams emitted from the light sources are reflected by the rotatable polygonal mirror toward the fixing device side, and rest parts of the laser beams are reflected by the rotatable polygonal mirror toward a side opposite from the fixing device side. Of the parts of the laser beams reflected by the rotatable polygonal mirror toward the fixing device side, the laser beam reflected toward the reflecting member provided at a position remotest from the rotatable polygonal mirror travels downward relative to a horizontal direction. A rotational axis of the rotatable polygonal mirror is inclined relative to a vertical direction.