Brother Kogyo Kabushiki-Kaisha

Toshiyuki Sano

Shintaro Sakaguchi

Masahito Saeki

Yusuke Ikegami

Tadao Kyotani

Masaaki Furukawa

Kotaro Haruta

Shoichiro Nishimura

Junya Sumida

Sota Hirano

Takahito Yamaji

Nao Itabashi

Toshio Furukawa

Chieko Mimura

Shunsuke Ishii

Keigo Goto

Kazutoshi Umeda

Yuichiro Minagawa

Hiroyasu Iwakoshi

An image forming apparatus is configured to perform image forming processing. The image forming apparatus includes a photosensitive drum, a main motor configured to generate a driving force, a drum clutch having a transmission state in which the driving force is transmitted to the photosensitive drum and a disconnected state in which the driving force is not transmitted to the photosensitive drum, a sheet sensor configured to detect a rear edge of a sheet upstream of the photosensitive drum in a sheet conveying direction, and a controller. In a case where a start command for subsequent image forming processing is not received after the sheet sensor detects a rear edge of a last sheet in image forming processing performed based on received print data, the controller executes drum clutch disconnection processing, and then executes main motor rotation stop processing.

Image forming apparatus

A sensor is located upstream of a conveyance roller in a sheet conveyance direction. A switch switches driving and stopping of a photosensitive drum. A controller performs a first mode process as a warm-up process of driving the conveyance roller and a fuser. The first mode process includes: driving the photosensitive drum for a particular time; in response to detecting a sheet within the particular time by the sensor, controlling the switch to continue driving the photosensitive drum after the particular time elapses and to discharge the detected sheet to a sheet discharge tray; and in response to not detecting the sheet within the particular time by the sensor, controlling the switch to stop driving the photosensitive drum at a time point when the particular time elapses, and driving the conveyance roller and the fuser to complete the warm-up process in a state where the photosensitive drum is stopped.

An image forming apparatus is configured to execute image forming processing of forming an image on a sheet. The apparatus includes a photosensitive drum, a fixing device including a heater and a roller, a main motor configured to generate a driving force, a driving mechanism having a connected state in which the driving force is transmittable to both the roller and the photosensitive drum, and a disconnected state in which the driving force is transmittable to the roller but is not transmitted to the photosensitive drum, a temperature sensor configured to detect a temperature of the fixing device, and a controller. In a case where the image forming processing is started, the controller sets the driving mechanism into the disconnected state, rotates the main motor at a preheating speed, and executes preheating processing in which the fixing device is heated by the heater.

An image forming apparatus includes: a main apparatus body having an image forming unit and a discharge tray; and a controller. The main apparatus body includes a conveyance path along which a sheet passed through the image forming unit is conveyed; a discharge path branched from the conveyance path and connected to the discharge tray; and a reconveyance path having a first path different from the discharge path and a second path for conveying the sheet to the image forming unit. In a double-sided printing, if a first sheet has passed through the first path when a forward end of a second sheet arrives at a predetermined position in the conveyance path, the controller conveys the second sheet to the first path and then conveys the second sheet to the second path.

In an image forming apparatus, a sheet is guided into a first conveyor path or a second conveyor path selectively when a first cover is in a closed position, and is ejected onto the first cover when the first cover is in an open position. Upon power-up, a controller causes a first conveyor roller to rotate but if the first cover is in the open position, when a sheet sensor detects a sheet, the controller does not cause a second conveyor roller to rotate, and causes a flapper to swing from a first position to a second position, and when a front end of the sheet reaches a position downstream of an upstream end of the flapper in a conveyance direction of the sheet conveyed by the first conveyor roller, the controller causes the flapper to swing from the second position to the first position.

A controller is configured to: when an inter-sheet time is shorter than or equal to a first time, maintain a developing roller in contact with a photosensitive drum during an inter-sheet time; when the inter-sheet time is longer than the first time and shorter than or equal to a second time longer than the first time, perform, during the inter-sheet time, at least part of temporary separation processing of temporarily separating the developing roller from the photosensitive drum in a state where the photosensitive drum is rotating; and when the inter-sheet time is longer than the second time, perform, during the inter-sheet time, at least part of temporary stop processing of separating the developing roller from the photosensitive drum and then stopping rotation of the photosensitive drum, and subsequently restarting rotation thereof and then bringing the developing roller into contact with the photosensitive drum.

Image forming apparatus with developing roller separation processing

An image forming apparatus includes a developing roller, a photo-interrupter, and a separation mechanism. The developing roller is movable between a contact position and a separated position. The photo-interrupter includes a light emitting element and a light receiving element. The separation mechanism includes a cam configured to move the developing roller between the contact position and the separated position. The cam includes a phase detection wall extending in a circumference direction. The phase detection wall has a first slit and a second slit. The first slit allows the light emitted from the light emitting element to pass therethrough when the developing roller is at the separated position. The second slit allows the light emitted from the light emitting element to pass therethrough when the developing roller is at the contact position. A size of the first slit in the circumferential direction is different from that of the second slit.

Image forming apparatus including cam having compact structure capable of detection of contact state and separated state of developing roller relative to photosensitive drum

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. The controller of the image forming apparatus is configured to perform: when a printing operation is performed onto the sheet ted 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.

Image forming apparatus configured to stop conveyance of sheet for prescribed time period before conveying sheet to photosensitive drum when sheet is fed from first tray

An image forming apparatus includes a photosensitive drum, a developing roller, a cam, a developing motor, a first transmission mechanism, and a second transmission mechanism. The cam moves the developing roller between a contacting position where the developing roller is in contact with the photosensitive drum and a separated position where the developing roller is separated from the photosensitive drum. The developing motor drives both the developing roller and the cam, and is rotatable in a normal rotating direction and a reverse rotating direction. The first transmission mechanism engages power transmission from the developing motor to the developing roller when the developing motor rotates in the normal rotating direction, and disengages the power transmission when the developing motor rotates in the reverse rotating direction. The second transmission mechanism can engage power transmission from the developing motor to the cam, irrespective of the rotating direction of the developing motor.

Image forming apparatus including common drive source for driving developing roller and cam that moves developing roller toward and away from photosensitive drum

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.

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.

Image forming apparatus including multiple photosensitive drums and multiple developing rollers

In response to determining that image forming in a color mode is performed on a first sheet and then image forming in a monochrome mode is successively performed on the second sheet, perform charging bias reduction processing gradually reducing a charging bias from first to second charging bias and developing bias reduction processing of gradually reducing a developing bias from first to second developing bias during a first inter-sheet period after the first sheet passes a first photosensitive drum and before the second sheet reaches the first photosensitive drum, and perform separation processing such that an execution period of the separation processing overlaps at least one of an execution period of the charging bias reduction processing and an execution period of the developing bias reduction processing, the separation processing being processing of controlling a moving mechanism to move a first developing roller from a contact position to a separation position.

Image forming apparatus which switches from color to monochrome mode with charging and developing bias reduction

An image forming apparatus, having first, second, and third photosensitive drums, a first developing cartridge including a first developing roller, a second developing cartridge including a second developing roller, a third developing cartridge including a third developing roller, an exposure device, a conveyer, and a moving mechanism, is provided. The first developing roller, the second developing roller, and the third developing roller are arranged in the recited order from upstream to downstream in a moving direction for the sheet to be conveyed. When the second developing roller is at the separated position thereof, the second developing cartridge coincides with a light path of the laser beam for scanning the first photosensitive drum. When the third developing roller is at the separated position thereof, the third developing cartridge coincides with a light path of the laser beam for scanning the second photosensitive drum.

Image forming apparatus having cartridge and exposure device

An image forming apparatus includes: a first developing roller movable between a first contact position and a first separated position; a second developing roller movable between a second contact position and a second separated position; and a controller. When a sheet interval is shorter than a first interval and is longer than or equal to a second interval, the controller maintains the first developing roller at the first contact position even after the completion of its development for a preceding sheet, controls the first developing roller to start development for a subsequent sheet, moves the second developing roller to the second separated position after the completion of its development for the preceding sheet, moves the second developing roller again to the second contact position, and controls the second developing roller to start development for the subsequent sheet after the second developing roller is moved again to the second contact position.

Image forming apparatus moving developing rollers toward and away from corresponding photosensitive drums based on sheet interval between two sheets

An image forming apparatus, having a casing, a cover, a photosensitive drum, a developing roller, a photo-interrupter, a moving mechanism to move the developing roller between a contacting position and a separated position, and a controller, is provided. The moving mechanism has a cam including, a first cam portion, a phase-detector wall including a first slit and a second slit, and a cam follower. When the cover moves from the open position to the closed position, the controller conducts a first initializing control to cause the cam to rotate in a reverse direction, and after detecting the first slit based on a time period, in which light in the photo-interrupter passes through one of the first slit and the second slit, cause the cam to stop rotating.

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Iwakura, Japan

Toshiyuki Sano