In an image forming apparatus, an image forming unit configured to form a toner image on a transfer medium includes four sets of a photoconductor drum and a development roller, respectively, for forming toner images of first, second, third and fourth colors, arranged in this order, in a direction opposite to a direction of movement of the transfer medium moving toward a detector configured to detect a toner image formed on the transfer medium. A controller executes a bias-corrective test image forming process in which a first bias-corrective test image of the first color is arranged in a position downstream of other three first bias-corrective test images, and a second bias-corrective test image of the first color is arranged in a position between two first bias-corrective test images selected among other three first bias-corrective test images, in the direction of movement of the transfer medium.

An image forming apparatus, including: a photoconductor; a developing device; a developer storage; a supplier configured to supply developer; an optical sensor; and a controller configured to execute: a developing process of developing an electrostatic latent image on the photoconductor; a usage-amount obtaining process of obtaining a usage amount of the developer; a supplying process of supplying the developer to the developing device every time when the obtained usage amount becomes equal to or greater than a first threshold; and a detecting process of detecting, by the optical sensor, an amount of the developer in the developing device every time when the obtained usage amount becomes equal to or greater than a second threshold larger than the first threshold, and wherein the controller is configured to execute the detecting process in a period different from a period in which the developing process is being executed.

An image forming apparatus, including: a photoconductor; a developing device; a developer storage; a supplier configured to supply developer; an optical sensor; and a controller configured to execute: a developing process of developing an electrostatic latent image on the photoconductor; a usage-amount obtaining process of obtaining a usage amount of the developer; a supplying process of supplying the developer to the developing device every time when the obtained usage amount becomes equal to or greater than a first threshold; and a detecting process of detecting, by the optical sensor, an amount of the developer in the developing device every time when the obtained usage amount becomes equal to or greater than a second threshold larger than the first threshold, and wherein the controller is configured to execute the detecting process in a period different from a period in which the developing process is being executed.

There are provided a printer device, a printing method, and a program that can appropriately output an exposure start signal without requiring a film detection device. A printer device includes a loading chamber into which a film cartridge is to be loaded, an exposure head device that is disposed to face a photosensitive surface of a film discharged from the film cartridge and exposes the film to light, a spreading roller that splits a developer pod of the film to spread a developer to the film, a transport roller that transports the film, and a load measuring device that measures a change in load occurring in a case where the film enters at least the spreading roller or the transport roller.

An image forming apparatus includes an image bearer, a toner image forming device, a plurality of image density detectors, and a controller. The plurality of image density detectors are disposed at predetermined intervals opposite the image bearer in a width direction of the image bearer. The controller causes the toner image forming device to form toner image patterns having an identical density at the plurality of positions on the image bearer and the plurality of image density detectors detects a density of the toner image patterns. Based on the detected density of the toner image patterns, the controller identifies multiple cyclic fluctuations of the density of the toner image patterns and adjusts an image forming condition based on the multiple cyclic fluctuations of the density of the toner image patterns to decrease an amplitude caused by the multiple cyclic fluctuations of the density of the toner image patterns.

A toner amount detection sensor has a first light receiving element, a second light receiving element, and a toner amount calculation unit. The first light receiving element is provided on a side opposite to a light emitting element with respect to a plane extending in a direction perpendicular to a surface of a transfer belt. The second light receiving element is provided at a position avoiding a plane containing the light emitting element and the first light receiving element and is provided separately from the first light receiving element. The toner amount calculation unit calculates the toner amount from the light quantity of the light equivalent to the specular reflection light received by the first light receiving element and the light quantity of the diffuse-reflected light received by the second light receiving element.

A toner amount detection sensor has a substrate, and a case housing. In the substrate, the light emitting element, the first light receiving element, and the second light receiving element are attached with an interval to the same first surface. In the substrate, first and second slits and are provided between a region where the light emitting element is attached and regions where the first light receiving element and the second light receiving element are attached. In the case housing, first and second light shielding walls and are disposed in such a manner as to extend to reach the inside of the first and second slits and when attached to the substrate and first and second light shielding walls and are provided between the light emitting element and the first light receiving element and between the light emitting element and the second light receiving element.

A developer cartridge is described. The developer cartridge detachably mountable on a tandem type photosensitive unit slidable to a drawn-out position and a mounted position with respect to an image forming apparatus body may include a casing; a developer carrier rotatably supported on one end portion of the casing for carrying a developer; a pair of upright portions arranged on another end portion of the casing at an interval from each other in the axial direction of the developer carrier to extend from another end portion of the casing in a detaching direction for the developer cartridge; and an elastically deformable coupling portion extending in the axial direction of the developer carrier for coupling the upright portions with each other.

A rotation detection device includes a light emitting portion, a light-passing control member, and a light receiving portion. The light-passing control member controls passing of the light from the light emitting portion. The light receiving portion outputs a light receiving signal based on the light received by the respective light receiving elements as detection signals representing detection results of the rotation by the rotator. A first virtual extended line that extends the first opening margin and a light-receiving-portion center line along the first direction passing through the respective light receiving elements at the light receiving portion pass through positions shifted from a rotational center of the light-passing control member. The light receiving portion is arranged such that the first virtual extended line corresponds to the light-receiving-portion center line, when the first opening margin passes through an optical path from the light emitting portion to the light receiving portion.

A magnetic carrier, which is suppressed from causing the loss and wear of a magnetic carrier coating resin even when used for a long time period, and achieves a stable image density and a reduction in toner scattering. In the magnetic carrier, the resin coating layer contains a resin A having a fluorine polymer moiety, the resin coating layer has an average thickness of 50 nm or more, a ratio F(x) (atomic %) of a fluorine atom detected at a position at a depth of x nm from a surface of a magnetic carrier particle by X-ray photoelectron spectroscopy satisfies formula (1) and formula (2), and when x represents an integer of 0 or more and 20 or less, F(x) satisfies formula (3):

5.0≤F(0)≤15  (1)

F(20)≤5.0  (2)

|F(x+1)−F(x)|≤7.5  (3).