An image-forming apparatus includes a photosensitive drum, a developing roller, a cam, a switching mechanism, a sheet tray, a sheet feed mechanism, a sheet sensor, and a controller. The switching mechanism rotates the cam to move the developing roller from a contact position in contact with the photosensitive drum to a separated position away from the photosensitive drum after development for the first sheet, if feeding of a second sheet is not started after elapse of a prescribed time period since detection of a first sheet. If image data for the second sheet is ready and upon elapse of a predetermined standby time period from elapse of the prescribed time period, the sheet feed mechanism starts feeding the second sheet toward the photosensitive drum and the switching mechanism rotates the cam to move the developing roller to the separated position in accordance with conveyance of the second sheet.

An image forming includes a dither processing unit that applies a dither matrix to an image; an exposure unit that exposes a photosensitive drum to form an electrostatic latent image based on the image to which the dither matrix has been applied; a development unit that develops, using a developing material on a developing roller, the formed electrostatic latent image; and a control unit that, based on a print setting change instruction by a user, increases a circumferential speed of the developing roller relative to the circumferential speed of the photosensitive drum and decreases a screen ruling of the dither matrix to be applied by the dither processing unit.

An image forming apparatus includes a first urging member including a first end portion and a second end portion positioned on an opposite side of a first end portion, the first urging member configured to urge a first pressing member to a first pressing position, and a second urging member including a third end portion and a fourth end portion, the second urging member configured to urge a second pressing member to a second pressing position, wherein the second end portion is arranged more distant from the first pressing member than the first end portion and is arranged between the first pressing member and the second pressing member in an axial direction, and the fourth end portion is arranged more distant from the second pressing member than the third end portion and is arranged between the first pressing member and the second pressing member in the axial direction.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference intensity information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

A measuring device that measures a distance between a first measurement target and a second measurement target. The measuring device includes a CPU that: calculates a first surface shape of the first measurement target based on first measurement data acquired from a first line sensor that emits first laser light to the first measurement target, and calculates a second surface shape of the second measurement target based on second measurement data acquired from a second line sensor that emits second laser light to the second measurement target; transforms at least one of a first coordinate system of the first line sensor and a second coordinate system of the second line sensor, to form a unified coordinate system; and calculates a distance between the first measurement target and the second measurement target in the unified coordinate system.

A photosensitive drum is rotatably supported in a main body. A developing cartridge is detachably mountable on the main body in a state where the photosensitive drum is supported in the main body. The developing cartridge includes a developing device and a frame. The developing device includes a developing roller disposed in confrontation with the photosensitive drum to supply developer to the photosensitive drum when the developing cartridge is mounted in the main body, and a developer-accommodating portion configured to accommodate developer. The frame includes a waste-developer-accommodating portion configured to accommodate waste developer and supports the developing device that is movable relative to the frame. The frame is disposed on an opposite side of the developing roller from the photosensitive drum. An urging member is disposed between the frame and the developing device to urge the developing roller toward the photosensitive drum.

Measures for controlling an engagement force between a photo imaging plate and a developer roller in a printing device are described. A motor is operated to generate rotational motion. The rotational motion is translated into linear motion. The linear motion causes an adjustment to the engagement force between the developer roller and the photo imaging plate. A characteristic of the motor is monitored. The motor is controlled on the basis of the monitored characteristic in order to maintain a desired engagement force between the developer roller and the photo imaging plate.

An image forming apparatus includes: a photosensitive drum; a developing roller; a separation mechanism for moving the developing roller between a contacting position contacting the photosensitive drum and a separated position separated from the photosensitive drum; a first tray; a first sheet feed mechanism for feeding a sheet from the first tray toward the photosensitive drum; a first sheet sensor for detecting passage of the sheet at a prescribed position; and a controller configured to perform: when a printing operation is performed onto the sheet fed from the first tray, feeding the sheet in the first tray to the prescribed position and maintain the sheet; moving, on or after the first sheet sensor detects the sheet, the developing roller to the contacting position; and feeding, after a prescribed time period has elapsed since the first sheet sensor detects the sheet, the sheet from the prescribed position toward the photosensitive drum.

An image-forming apparatus includes a photosensitive drum, a developing roller, a cam, a switching mechanism, a sheet tray, a sheet feed mechanism, a sheet sensor, and a controller. The switching mechanism rotates the cam to move the developing roller from a contact position in contact with the photosensitive drum to a separated position away from the photosensitive drum after development for the first sheet, if feeding of a second sheet is not started after elapse of a prescribed time period since detection of a first sheet. If image data for the second sheet is ready and upon elapse of a predetermined standby time period from elapse of the prescribed time period, the sheet feed mechanism starts feeding the second sheet toward the photosensitive drum and the switching mechanism rotates the cam to move the developing roller to the separated position in accordance with conveyance of the second sheet.

A process cartridge detachably mountable in an image forming apparatus includes a toner cartridge for accommodating a developer; a developer roller; and a driving force receiving assembly for receiving a driving force of the image forming apparatus and driving the developer roller to rotate; and further includes a first stopper and a second stopper provided at a bottom of the toner cartridge, and the first stopper and the second stopper being movable relative to the toner cartridge in a direction perpendicular to an axial direction of the driving force receiving assembly; and when the first stopper and/or the second stopper move, a driving force receiving head of the driving force receiving assembly is movable in an axial direction of the driving force receiving assembly. The process cartridge can realize separation and contact between a developer roller and an image forming apparatus.