A fixing device includes: a non-contact heating unit configured to heat a recording medium in a non-contact manner; and a contact heating unit configured to press and heat the recording medium on a downstream side of the non-contact heating unit in a conveyance direction of the recording medium, in which the non-contact heating unit controls an amount of heat applied to the recording medium according to information on whether the recording medium is black or not, and a thickness of the recording medium, and the contact heating unit controls the pressure applied to the recording medium according to the thickness regardless of whether the recording medium is black or not.

A heating device includes a first temperature sensor and a second temperature sensor that detect a temperature of at least one of a first rotator, a second rotator, and a heater that heats at least one of the first rotator and the second rotator. The first temperature sensor is disposed outboard from an increased conveyance span where an increased size sheet having an increased width in a longitudinal direction of the heater is conveyed. The second temperature sensor is disposed outboard from a decreased conveyance span where a decreased size sheet having a decreased width in the longitudinal direction of the heater is conveyed. The decreased conveyance span is smaller than the increased conveyance span. The second temperature sensor is disposed within the increased conveyance span and disposed opposite the first temperature sensor via a center of the increased conveyance span in the longitudinal direction of the heater.

A fixing device includes a movable belt; and a planar heat-generating section that is in contact with the belt and in which, among plural heat-generating portions provided in a movement direction of the belt, a heat-generating portion on an upstream side in the movement direction of the belt has a larger heat generation amount than a heat-generating portion on a downstream side.

According to one embodiment, a temperature control device stores a fixing device temperature estimation value and a storage time obtained by WAE control in a memory at any time during operation. After an electric power supply to the temperature control device is stopped, the next time the electric power supply is started, an electric power supply stop period until the electric power supply is started is calculated. If the electric power supply stop period is shorter than a set time, the WAE control is started by using the stored fixing device temperature estimation value, and if the electric power supply stop period exceeds the set time, the WAE control is started based on an initial set value.

An image forming apparatus includes a heating member energization control circuit that estimates a temperature of a fixing rotating body, based on a temperature detection result of the fixing rotating body, which is heated by a heating member and heats a toner image formed on a medium to fix the toner image on the medium, by a temperature sensor, a power supply voltage of a power supply source, and an energization pulse for controlling energization to the heating member, and outputs an energization pulse for controlling power to be supplied to the heating member, based on the estimated temperature and the temperature detection result. The apparatus further includes a controller that acquires a power supply voltage detection result by a communication interface via a network, from another apparatus which holds a power supply voltage detection result by an image forming apparatus with a power supply voltage detection function, provided with a power supply voltage detection circuit that detects a power supply voltage value of a same power supply source as the power supply source, and inputs the acquired power supply voltage detection result to the heating member energization control circuit, as a power supply voltage value of the power supply source.

An image forming apparatus includes two rotators, a driver driving the rotators, a heating device to heat the rotator, a blower blowing air to the heating device, a temperature detector, a recording medium detector, a cover, an open-close detector, and circuitry. The circuitry detects an abnormal state and stops heat generation, determines whether the cover is closed using the open-close detector, controls the blower to blow air when the cover is closed, determines whether the recording medium is in the nip using the recording medium detector, controls the driver to rotate the two rotators when the cover is closed and no recording medium is in the nip, determines whether a temperature detected is equal to or lower than a threshold value before the cover is opened, and controls the blower to decrease an air volume when the temperature detected is equal to or lower than the threshold value.

A heating device includes a first rotator, a second rotator, a heater, and a first, second and third temperature sensors. The second rotator contacts an outer circumferential surface of the first rotator to form a nip through which a recording medium passes. The heater heats the first rotator. The first temperature sensor is disposed outside a space extending from a first region through which a minimum recording medium passes and detects the temperature of the first rotator. The second temperature sensor is disposed outside the space extending from the first region and detects the temperature of the heater. The third temperature sensor is disposed outside the space extending from the first region and detects the temperature of the second rotator. At least one of the second temperature sensor or the third temperature sensor is disposed outside a space extending from a second region through which a maximum sheet passes.

According to one embodiment, there is provided a temperature abnormality detection circuit provided in a temperature control device includes a target temperature determination circuit, a difference arithmetic circuit, a temperature abnormality determination circuit, and a storage circuit. The temperature abnormality detection circuit is configured to determine the presence or absence of temperature abnormality by a response situation of a detected temperature by a temperature sensor, calculate a current temperature difference from the detected temperature acquired by the temperature sensor if it is determined that there is a temperature abnormality and an estimated WAE temperature value, and determine whether the temperature sensor is abnormal or the control circuit side is abnormal based on the result of comparison between the temperature difference and a preset threshold value.

A medium drying device includes a transport roller pair as a transport unit that transports a medium and a heat roller pair as one heating unit that heats the medium transported by the transport roller pair and is provided in a transport direction of the medium, in which the medium is configured to be transported to a heating area by the heat roller pair a plurality of times.

A heating efficiency 600 includes a substrate 610 and a plurality of heat generating elements 523a to 623f which are provided on both surfaces of the substrate 610 and which generate heat, and heats a fixing belt in contact with an inner peripheral surface of the fixing belt. The plurality of heat generating elements 623a to 623f are different from each other in length with respect to a widthwise direction, and at least three of the heat generating elements are provided on a front surface of the substrate 610 which is a side where the heater 600 contacts the inner peripheral surface of the fixing belt 600, and at least one of the heat generating elements is provided on a back surface. A longest heat generating element 623b, in length with respect to the widthwise direction, of the plurality of heat generating elements 623a-623f is provided on the front surface. Further, as regards the heat generating elements 523a-623c provided on the front surface, with respect to a rotational direction of the fixing belt, the longest heat generating element 623b in length with respect to the widthwise direction is disposed between the heat generating element 623a and the heat generating element 623c.