An image forming apparatus includes a fixing unit, a switching element, and a controller. The controller controls the switching element on a half-cycle basis of an alternating current. A period in which the electric power is supplied to the heater within a period of a half-cycle of the alternating current is divided into at least one first power supply period and a second power supply period longer than one first power supply period. A length of a sum of the at least one first power supply period is a length from 1/6000 to 1/40 of one cycle of the alternating current. A sum of electric power supplied in the at least one first power supply period and electric power supplied in the second power supply period is determined depending on a difference between a temperature and a target temperature of the fixing unit.

A driving force transmission device includes a drive gear, a driven gear, which includes a gear portion and a partially toothless gear portion, rotates by the gear portion meshing with the drive gear, stops rotating in response to the partially toothless gear portion facing the drive gear, a first cam member and a second cam member which operate in conjunction with the driven gear, a first elastic member for urging the first cam member, a follower member to which urging force is applied by a second elastic member and which is moved by the second cam member, and a contact portion for coming into contact with the first cam member by urging force of the first elastic member. The first cam member includes a home cam surface for coming into contact with the contact portion so that rotation of the driven gear is limited.

A series of conveyance paths to convey a recording medium is formed across a printer and a post-processing device in a printing system. The printing system includes: a detection unit that detects that the post-processing device has entered a predetermined state; and a paper feeding control unit that limits the number of recording media fed to the conveyance path, when it is not detected that the post-processing device has entered the predetermined state, based on the number of recording media conveyable to the post-processing device after the post-processing device enters the predetermined state.

An image density detector for detecting image density of an image borne by an image bearer includes a reference board, a light emitter, a light receiver, an image density calculator, and an image density detecting condition corrector. The reference board has a spectral reflectance distribution closer to a spectral reflectance distribution of the image forming material than a spectral reflectance distribution of white. The light emitter emits light to the reference board and the image borne by the image bearer. The light receiver receives the light reflected from the image and the reference board. The image density calculator calculates the image density of the image based on an output of the light receiver receiving the light reflected from the image. The image density detecting condition corrector corrects an image density detecting condition based on an output of the light receiver receiving the light reflected from the reference board.

An image forming device includes a device body; a conveyance table that is inserted into and pulled out of the device body and that forms a conveyance path for a sheet; a sheet mount tray; a paper feeder that feeds the sheet from the sheet mount tray to the conveyance path; and a movable support that movably supports the paper feeder on the conveyance table in a state where the conveyance table is pulled out of the device body. The paper feeder covers a predetermined part of the conveyance path in a state where the paper feeder disposed on the conveyance table is inserted into the device body, the sheet mount tray is disposed in the device body and separates from the paper feeder when the conveyance table is pulled out of the device body, and the paper feeder moves away from the predetermined part.

An image forming apparatus includes a process unit, a controller, and a fixing unit including a heater. The process unit is configured to form a developer image on a sheet. The heater is configured to be applied with an AC voltage, and to heat the sheet to thereby fix the developer image to the sheet. The controller is configured to perform: executing a continuous supply control in which the heater is continuously energized; acquiring an initial voltage dropping level of the AC voltage and a recovery time during the executing the continuous supply control; and setting a power supply control to control energization of the heater for starting up the heater on the basis of the acquired initial voltage dropping level and the acquired recovery time.

An image-forming apparatus for forming an image on a sheet includes an image-forming unit that forms the image on the sheet, and a conveying unit that conveys the sheet on which the image is formed by the image-forming unit. The conveying unit includes a pair of first rollers that discharges the sheet to the outside of the image-forming apparatus and a pair of second rollers that conveys the sheet in a direction in which the sheet is discharged to the outside of the image-forming apparatus and that subsequently switches a conveyance direction of the sheet to an opposite direction to convey the sheet again to the image-forming unit. The pair of the first rollers and the pair of the second rollers partially overlap when viewed in a width direction of the sheet that is perpendicular to the conveyance direction of the sheet.

A moving mechanism of a reading unit includes a driving pulley, a plurality of driven pulleys which are rotatably driven, an endless belt which is engaged and rotates between the driving pulley and the plurality of driven pulleys, and attracts the reading unit, and a biasing unit which applies tension to the endless belt, in the endless belt, an attraction section which is a belt section that extends along the auxiliary scanning direction, and which attracts the reading unit, is formed between a first driven pulley and a second driven pulley, the driving pulley is provided at a position separated from the attraction section in the main scanning direction, and a biasing force of the biasing unit is applied to the belt section excluding the attraction section in the endless belt.

An electrical connecting member electrically connects between two conductive members comprising. The electrical connecting member includes a coil spring part formed by winding a wire around a coil axis. The electrical connecting member comes into contact with one of the conductive members with elastic force in a circumferential direction around the coil axis and comes in contact with the other of the conductive members with elastic force in an axial direction of the coil axis so that the conductive members are electrically connected.

A drive transmission device includes: a first rotating member that rotates with driving power received from a driving source, a second rotating member that rotates with driving power from the first rotating member, and a driving-side engagement member and a driven-side engagement member for transmitting the driving power of the first rotating member to the second rotating member, wherein the driving-side engagement member and the driven-side engagement member engage with each other in a state in which the first rotating member is rotating whereby a power applying portion and a power receiving portion engage with each other while resisting against a second biasing power.