A fixing device includes an endless fixing rotator, a temperature detector, a pressure rotator, a nip formation pad, and a plurality of heaters. The temperature detector detects a temperature of the fixing rotator. The pressure rotator is in contact with an outer circumferential surface of the fixing rotator. The nip formation pad is disposed inside a loop of the fixing rotator to form a nip between the fixing rotator and the pressure rotator. The plurality of heaters heat an inner circumferential surface of the fixing rotator and includes a first heater and a second heater. The first heater uniformly generates heat in a longitudinal direction of the fixing rotator and independently receives power. The second heater generates different heat generation amounts at different positions in the longitudinal direction of the fixing rotator and receives power together with the first heater.

According to one embodiment, a temperature control device includes a temperature estimation unit and a frequency generation unit. The temperature estimation unit is configured to estimate a temperature of an object being heated by an induction heating coil, the temperature being estimated based on a frequency of a drive signal supplied to an inverter connected to the induction heating coil. The frequency generation unit is configured to set the frequency of the drive signal based on the temperature estimated by the temperature estimation unit, a detected temperature of the object from a temperature sensor, and a target temperature for the object.

An image forming apparatus includes a developing device, an image bearing member, an image density detecting portion, a toner content detecting portion, a humidity sensor, a supplying portion, and a controller configured to control the supplying portion so that a toner content is between an upper limit and a lower limit thereof. The controller can execute setting control in which the target value of the toner content is set on the basis of an image density of a reference toner image. The controller sets the lower limit until execution of subsequent setting control, wherein the lower limit is higher when a humidity is a first humidity and an average image ratio is a first ratio than when the humidity is a second humidity higher than the first humidity and the average image ratio is a second ratio larger than the first ratio.

In an image forming apparatus of a direct transfer system, when in a region where a transfer nip portion of a photosensitive drum is formed, a region in which the toner image can be formed is defined as a first region, and a region where the recording medium does not pass while the recording medium is conveyed by the transfer nip portion is defined as a second region, in forming the toner image on the recording medium, the photosensitive drum enters the transfer nip portion in a state where the second region of the photosensitive drum includes a region in which an absolute value of a surface potential is smaller than an absolute value of a surface potential of a region in which the toner image is not formed in the first region.

An image forming apparatus including: a fixer that fixes a toner image formed on a recording medium by pressing and heating the recording medium nipped in a nip portion formed by causing two rotating bodies to pressedly abut on each other, and conveying the recording medium by rotating the rotating bodies; a motor that drives the rotating bodies by transmitting a torque to at least one of the rotating bodies; a torque detector that detects the torque transmitted to the rotating body by the motor; a temperature detector that detects temperature of the rotating body; a speed detector that detects a conveyance speed for conveying the recording medium by the fixer; and a controller that corrects the detected torque based on at least any one of the detected temperature and the detected conveyance speed and predicts a life of the fixer based on the corrected torque.

An image forming apparatus that forms an image on a sheet includes: a rotating body that forms the image; a motor that rotationally drives the rotating body; a current measurer that measures a motor current flowing through a current supply path including a winding of the motor at a measurement timing that is a timing after the motor is started; a torque acquisitor that acquires a torque value of the motor, based on a measured value of the motor current; and a corrector that performs correction to cancel a current change amount based on a characteristic change depending on a temperature state of the motor at the measurement timing, in acquisition of the torque value by the torque acquisitor.

An image forming apparatus includes an image forming unit to form an image based on an image forming condition; a sensor to measure a measurement image formed by the image forming unit; and a controller to obtain information correlated with a change in density of an image to be formed by the image forming unit, control the sensor to measure the measurement image, determine first data related to density of the image to be formed by the image forming unit, determine, based on a result of measuring the measurement image, second data related to density of the image to be formed by the image forming unit, and generate the image forming condition based on a weighted average of the first data and the second data.

A heater unit is detachably attachable to an image forming apparatus, the image forming apparatus including an intake port configured to be provided in an exterior of a body of the image forming apparatus, and the heater unit includes: a power plug configured to receive power from a commercial power supply; a heater configured to generate heat by the power received from the power plug; a fan configured to rotate by the power received from the power plug and blow air warmed by the heater; and a screw hole configured to fix the heater unit to the image forming apparatus by a screw, wherein the heater unit is configured to be mounted on the intake port so that an air flow generated by the fan of the heater unit flows into the intake port.

An image forming apparatus includes a container that contains a developer, a temperature information acquisition unit that acquires temperature information of the container, and a control unit that controls an image formation operation for forming an image and, in the image formation operation, the control unit executes a suspension operation for suspending the image formation operation in the case that tt.sub.oth(t.sub.oth0) is satisfied, where t is defined to be an elapsed time from when a temperature corresponding to the temperature information of the container exceeds a predetermined threshold temperature T.sub.th, and where t.sub.oth is defined to be an exceeding time threshold value related to a period during which the temperature corresponding to the temperature information of the container remains higher than the threshold temperature T.sub.th.

An image forming apparatus includes a developing section, an image carrier, a deviation correction section, a specific pixel detection section and a determination section. The developing section forms a visible image on a photoconductor for each type of developer. The image carrier carries the visible images formed in a plurality of the developing sections. The deviation correction section corrects position deviation of the plurality of visible images formed on the image carrier. The specific pixel detection section detects the specific pixel used to form an image with a plurality types of developers. The determination section determines execution of correction in the deviation correction section according to information indicating an amount of the specific pixels.