An image forming apparatus includes a fixing unit including a heater; a bidirectional thyristor for supplying electric power form an AC power source to the heater in a conduction state and for cutting off supply of the electric power from the AC power source to the heater in a non-conduction state; a control unit for outputting a control signal for controlling the conductive state or the non-conduction state of the bidirectional thyristor; and a DC voltage source for supplying electric power for conduction of the bidirectional thyristor by the control signal outputted from the control unit. The control unit controls the heater in a predetermined control cycle on a one half-wave unit basis of an AC voltage of the AC power source. The control unit outputs a plurality of control signals in one half-wave of the AC voltage.

An image forming apparatus includes a main body housing, a first cartridge to store first developer, a second cartridge to store second developer, a first temperature sensor to detect an inside temperature as a temperature inside the main body housing, and a controller configured to calculate a first control temperature corresponding to the first cartridge, using the detected inside temperature and a first coefficient to be multiplied by the inside temperature, calculate a second control temperature corresponding to the second cartridge, using the detected inside temperature and a second coefficient to be multiplied by the inside temperature, the second coefficient being different from the first coefficient, and perform cooling control to cool an inside of the main body housing when at least one selected from the first control temperature and the second control temperature is higher than a particular threshold.

When a toner image is continuously formed on a plurality of recording materials, and the toner image is fixed onto the recording materials, a conveyance control portion changes throughput, which is the number of recording materials to be conveyed per unit time, from first throughput to second throughput, which is slower than the first throughput, when a second detection temperature detected by a second temperature detecting portion that detects a temperature at an end of a heating member in a longitudinal direction of the heating member perpendicular to a conveyance direction of the recording materials exceeds a first threshold, and changes the throughput from the second throughput to third throughput, which is slower than the second throughput, when the second detection temperature exceeds a second threshold, which is higher than the first threshold, after the recording material conveyed at the second throughput reaches the nip.

An image forming apparatus includes an attachment portion to which any one of a first fixing apparatus and a second fixing apparatus is selectively attached, and a power supply circuit including a plurality of power supply paths. The first fixing apparatus includes a plurality of first heating elements grouped into a plurality of groups, and a number of the plurality of groups is equal to a number of the plurality of power supply paths. The second fixing apparatus includes at least one second heating element grouped into at least one group whose number is smaller than the number of the power supply paths. In a state where the second fixing apparatus is attached to the image forming apparatus, a power supply path of the plurality of power supply paths in which a power line has a largest allowable current value is electrically connected with the second heating element.

A printing device having a heating apparatus arranged to heat an image substrate, a temperature sensor associated with the image substrate, and a processor communicatively coupled to the heating apparatus. During a simulation mode of the printing device, the processor determines the heating power of the heating apparatus, predicts a temperature of the image substrate based on the heating power, compares the predicted temperature to a measured temperature of the image substrate by the temperature sensor, determines a calibration offset when the measured temperature deviates from the predicted temperature, and selectively generates a control signal for use in calibrating the temperature sensor based on the calibration offset.

An image forming apparatus includes: an image. forming unit configured to form an image on an image bearing member based on an image forming condition, an optical sensor including: a light emitter configured to irradiate the image bearing member with light based on a supplied current; and a light receiver configured to receive reflected light of the light emitted from the light emitter; a temperature detector configured to detect a temperature of the optical sensor; and a controller configured to: control the image forming unit to form a detection image on the image bearing member; control the optical sensor to detect reflected light from the detection image; and adjust the image forming condition based on a result of detecting the detection image by the optical sensor. The controller is configured to control the light emitter to emit light; and generate a correction condition.

An image forming apparatus includes a plurality of temperature-influence members, a first-point temperature acquisition unit, a second-point temperature estimation unit, and a controller. The plurality of temperature-influence members have influence on a temperature of a recording medium on which an image is formed. The first-point temperature acquisition unit is configured to detect or estimate a temperature of the recording medium at a first point. The second-point temperature estimation unit is configured to estimate a temperature of the recording medium at a second point, based on a detection result of at least one of a temperature of the recording medium at a point different from the second point and a temperature of a member or atmosphere. The controller is configured to control the plurality of temperature-influence members, based on an acquisition result from the first-point temperature acquisition unit and an estimation result from the second-point temperature estimation unit.

In one aspect an apparatus for use in an electrographic printer is described. The apparatus includes a housing defining a cavity, a developer roller, a developer electrode for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

An image forming apparatus includes a heater, a fixing device, and a controller. The heater includes a heat generator that generates heat when the heater is turned on. The fixing device may fix a developer image on a surface of an image forming medium using the heat from the heat generator. The controller detects a voltage of a power supply for supplying electric power to the heater, and determines an occurrence of an abnormality in the heater if a voltage drop amount at the time the heater is turned on as compared to a case in which the heater is turned off is smaller than a first threshold value.

According to one embodiment, an image forming apparatus includes an image carrier, an exposing apparatus, a developing device, a transfer device, a fixing device, a history acquisition unit, an estimation unit, and an output unit. The exposing device exposes the image carrier to form an electrostatic latent image on the image carrier. The developing device includes a layer forming member to form a toner layer on a developing roller and forms a toner image by developing the electrostatic latent image. The transfer device transfers the toner image to a sheet. The fixing device fixes the toner image to the sheet. The history acquisition unit acquires a history regarding a temperature around the developing device. The estimation unit estimates a possibility that an image defect caused by the layer formation may occur on the basis of the history. The output unit outputs estimation results of the estimation.