A control unit controls power to be supplied to a common power supply path in a first period, using a selected first temperature detection member, and controls power to be supplied to the common power supply path in a second period, using a selected second temperature detection member. The first temperature detection member has a higher detected temperature than that of the second temperature detection member, and in the second period, the first detected temperature and the second detected temperature fall within a temperature range between a first temperature and a second temperature lower than the first temperature.

A thermopile sensor that is a temperature measuring device of a fusing device is held on a substrate. The substrate is provided with a cylindrical member extending in front of the thermopile sensor and an aperture disposed at an end of the cylindrical member.

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.

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 toner image forming unit, a fuser including a heater, a temperature sensor that detects a temperature of the fuser, and a controller. The controller exercises a standby control that includes repeating a control cycle, measuring a temperature fluctuation period that is a time period from start of energizing the heater to an end of the control cycle, and setting an energization amount for a next control cycle, based on the measured temperature fluctuation period. The control cycle includes energizing the heater with an energization amount during a preset heating period when the detection temperature has dropped to a temperature below the target standby temperature, and waiting until the detection temperature drops to the target standby temperature in a case where the detection temperature has risen to a temperature equal to or above the target standby temperature after the preset heating period has elapsed.

A light emitting device includes: a member having a first surface facing in one direction and a second surface facing an opposite side to the first surface; a light emitter that is disposed at the first surface, generates heat due to light emission, and has a lower stiffness than the member; and a heater that is disposed at the second surface of the member, and heats the member from the second surface.

An image forming system includes: an image forming apparatus that includes a transfer device that transfers a toner image onto a sheet and a fixing device that fixes the toner image; a sheet heating device that heats the sheet on an upstream of the fixing device in a sheet conveyance direction; a first detector that detects a temperature inside the image forming apparatus; a second detector that detects a temperature of the sheet before the sheet heating device heats the sheet; and a controller that causes the sheet heating device to heat the sheet based on a detection result by the second detector and a sheet passing condition of the sheet, and corrects at least one of a transfer current and a transfer voltage in the transfer device based on a detection result by the first detector in a case where the sheet heating device heats the sheet.

An image forming apparatus which includes a motor, a first power supply unit that supplies a first voltage to the motor, and a second power supply unit that supplies a second voltage, which is higher than the first voltage, to the motor, and a central processing unit (CPU) that controls supply of the second voltage from the second power supply unit to the motor while maintaining supply of the first voltage from the first power supply unit to the motor.

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.

An image forming apparatus, temperature control method, and temperature control device are provided. The apparatus includes the device, which acquires a first temperature difference between a temperature estimation value of a fixer, which is obtained by simulating a member temperature of a temperature control target serving as a heat capacitor-resistor circuit at an initial stage of operation of the fixer, and a detected temperature detected by a temperature sensor, and acquires a second temperature difference between a temperature estimation value of the fixer, which is obtained during an operation after the first temperature difference is acquired, and a detected temperature. The device calculates a difference between the first temperature difference and the second temperature difference, determines that the detected temperature is abnormal in response to the difference being equal to or greater than a threshold value, and performs temperature control for correcting a target temperature of the member temperature.