An image forming apparatus includes a stack portion on which a sheet is to be stacked, a regulating portion, a first detection device which includes a rotary variable resistor, a second detection, and a control unit. The regulating portion regulates a position of an edge of the stacked sheet. The first detection device outputs a detection signal based on the rotary variable resistor. The rotary variable resistor rotates in accordance with the sheet edge position regulated by the regulating portion. The second detection device detects presence or absence of the stacked sheet. The control unit calculates a calculated sheet width of the stacked sheet based on the output detection signal. The control unit sets the calculated sheet width after a first predetermined time has elapsed since the second detection device detects that the sheet is stacked on the stack portion as a detected sheet width of the stacked sheet.

A decurling device is provided on a downstream side with respect to a fixing device in a medium transporting direction and straightens a curl formed in a medium transported to the decurling device. The decurling device includes a bending unit extending across the medium transporting direction and having a guiding surface that guides a leading end of the medium, the leading end coming into contact with the guiding surface, the bending unit bending the medium in a decurling direction by using the guiding surface; an urging unit that urges the bending unit toward the medium; and a single or plural rotating members provided on a part of the guiding surface of the bending unit and rotating by coming into contact with the medium that is in contact with the guiding surface.

A heating apparatus including: a first load; a first switch element configured to switch supply and shut-off of power from an AC power source to the first load; a second load; a second switch element configured to switch supply and shut-off of power from the AC power source to the second load; a control unit configured to control the first and the second switch elements to supply power to either the first load or the second load; a first detection unit configured to detect whether the first switch element is in a conductive state; a second detection unit configured to detect whether the second switch element is in a conductive state; and a determination unit configured to determine whether both of the first load and the second load are in a state of being supplied with power, based on detection results of the first and the second detection units.

A fixing device includes a heater, a switching element, a zero-cross detecting portion, a controller, a power source, a driving portion. In a case that an amount of electric charge charged in the power source is predetermined value or more, the controller outputs a first signal to the driving portion so that a time in which a current is passed from the power source to the switching element is a first time. In a case that the amount of the electric charge is less than the predetermined value, the controller outputs a second signal to the driving portion so that the time in which the current is passed from the power source to the switching element is a second time shorter than the first time.

A recording material determination device includes a transmission unit, a drive unit, a reception unit, and a control unit. The drive unit outputs a drive signal for transmitting an ultrasonic wave from the transmission unit to the reception unit. The control unit determines a type of a recording material, based on a first value of the ultrasonic wave through the recording material received by the reception unit in a first mode for outputting a first number of drive signals from the drive unit in a first period, and a second value of the ultrasonic wave through the recording material received by the reception unit in a second mode for outputting a second number of drive signals from the drive unit in a second period. The second number of drive signals is greater than the first number of drive signals.

A printing system includes a printing apparatus that prints an image on a sheet, a sheet processer that executes sheet processing, and a sheet detection sensor that detects a sheet on which the sheet processing is performed not in association with the printing of an image, where the printing of an image is restricted in response to detection of a sheet by the sheet detection sensor.

A fixing unit or device that can be used in an image forming apparatus includes a first heater element that is formed of a material that increases in electrical resistance with increases in temperature. A controller of the fixing unit is configured to vary a duty ratio of electric power applied to the first heater element during a start-up operation in which the temperature of the first heater element is raised to a target operating temperature. By varying the duty ratio during the start-up operation, changes in the resistance of the first heater element with the heating can be compensated. For example, the duty ratio can be increased during the course of the start-up to achieve the target operating temperature faster.

A fixing device includes a fixing rotator over which a recording medium bearing an image is conveyed. A first heater heats the fixing rotator and generates heat evenly in a maximum conveyance span where the recording medium having a maximum width in a width direction of the recording medium is conveyed. The maximum width is available for the fixing rotator. A second heater heats the fixing rotator and generates heat in the maximum conveyance span. The second heater includes a first portion that generates heat in a first heat generation amount and a second portion that generates heat in a second heat generation amount that is greater than the first heat generation amount of the first portion.

A printing device comprises a housing, a communication interface configured to communicate with a server, and a controller. The printing device is configured to operate either in a contract mode or in a normal mode. The housing is configured such that one or more consumables including a first type consumable and a second type consumable are attachable. The first type consumable is dedicated for the contract printing, and the second type consumable is usable for printing in both the contract mode and the normal mode. The controller is configured to activate the contract mode in response to an activation instruction from the server. In a case where the second type consumable is attached to the housing when the contract mode is activated, the controller changes a state of the printing device to a contract printing state in which the contract printing is activated after activating the contract mode.

A medium conveying apparatus includes a housing including an accommodation portion provided with a guide portion at an end portion in a width direction, a tray accommodated in the accommodation portion so as to be pulled out, and including a placing surface for placing an ejected medium, and an engaging portion provided on a side surface of the tray, to engage the guide portion. The guide portion includes a pair of rails inclined upward and having a predetermined width. The engaging portion includes two protrusions provided so as to slide between the pair of rails and located apart from each other by a predetermined distance. By locating the two protrusions between the pair of rails, the tray is positioned at a predetermined position with respect to the housing with a front end portion of a downstream side in the medium ejecting direction located upward.