An image forming apparatus determines, in a first mode, an image forming condition according to characteristic data, which is input by a user and represents characteristics of a sheet contained in a sheet container, causes the sensor to detect characteristics of a sheet, and stores characteristic data according to a result of the detection into the memory. The image forming apparatus determines, in a second mode with the characteristic data being stored in the memory, an image forming condition, based on the characteristic data stored in the memory before a result of detecting a characteristic of a sheet by the sensor is obtained. The image forming apparatus causes, in the second mode with the characteristic data being not stored in the memory, the sensor to detect characteristics of a sheet, and determines an image forming condition based on a result of the detection.

A fixing device includes a pair of fixing members disposed to face each other in a fixing area, a movable member movably supporting at least one of the fixing members between first and second positions, a driving device including a contact member and a drive source to move the movable member between the first and second positions, and a controller that controls the driving device, and if a temperature of the one of the fixing members is equal to or higher than a preset temperature when the driving device moves the movable member from the second position to the first position, changes the control to make driving force constantly exceed a rotational load of the driving device in accordance with advancement of a time of increase in the rotational load as compared with when the temperature of the one of the fixing members is lower than the preset temperature.

An image forming apparatus includes a first image forming unit that develops a first latent image using a first developer so that a first developer image is developed with the first developer, a second image forming unit that develops a second latent image using a second developer, which is lower in saturation or higher in light-permeability in comparison to the first developer, so that a second developer image is developed with the second developer, a transfer part that transfers the first developer image and the second developer image to a medium, and a control part that controls an amount of the second developer used to develop the second developer image according to a type of the medium.

A fixing device includes a fixing rotator, an opposed rotator disposed opposite the fixing rotator, a pressure pad, a lateral end heater, and a thermal conduction aid. The pressure pad presses against the opposed rotator via the fixing rotator to form a fixing nip between the fixing rotator and the opposed rotator. The lateral end heater is disposed on the pressure pad to heat a lateral end of the fixing rotator in the axial direction of the fixing rotator. The thermal conduction aid is interposed between the pressure pad and the fixing rotator to decrease a temperature gradient of the fixing rotator in an axial direction of the fixing rotator. The pressure pad includes a nip-side face disposed opposite the thermal conduction aid. The lateral end heater includes a nip-side face being disposed opposite the thermal conduction aid and projecting beyond the nip-side face of the pressure pad.

An image forming apparatus, including: an image forming portion that forms an image on a recording material based on image data; a fixing portion that includes a heater having a plurality of heat generating members arranged in a direction perpendicular to a conveying direction of a recording material, and that fixes the image to the recording material using heat of the heater; a storage portion that stores history information on the recording material when image forming operation is performed in which the image forming portion forms the image and the fixing portion fixes the image, a control portion that sets power to be supplied to the heat generating members based on the history information before a type of the recording material on which the image is formed or content of the image data of the image to be formed on the recording material is determined.

An image forming apparatus includes an image forming part, a fixing device, a fixing temperature sensor, a drive device, a printed sheet number counting part, a fixing voltage power supply, a controller, and an apparatus external temperature sensor. The controller can perform a cooling mode in which, when a number of continuous printed sheets at a reference speed exceeds an upper limit number, a number of printed sheets per unit time is gradually decreased to suppress an increase of an apparatus internal temperature. The controller sets the upper limit number based on a temperature difference between the fixing temperature detected by the fixing temperature sensor and the apparatus external temperature detected by the apparatus external temperature sensor.

An image forming apparatus includes a fixing unit including a tubular film, a pressure roller, and a heater including a heating element. The apparatus further includes a control unit configured to calculate an accumulated electrical energy supplied to a portion of the heating element. The portion of the heating element is located in an area corresponding to a second area of the nip portion. The second area is an area of the nip portion through which the recording material conveyed to the nip portion is not passed. The control unit is configured to determine an operation of heat leveling, which is performed for leveling a heat distribution in the nip portion after the recording material had passed the nip portion, based on the calculated accumulated electrical energy.

According to an embodiment, an image forming apparatus measures a temperature of a pressing member and controls heat generation of a heater such that the measured temperature approaches a control temperature. Further, the image forming apparatus sets, before starting image formation of one job including image formation, one candidate temperature of a plurality of predetermined candidate temperatures different from each other as the control temperature on the basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job.

An image forming apparatus includes: a contact portion that is disposed at a position. where the contact portion is contactable with a recording medium; a cooler that cools the recording medium; and a hardware processor that controls a cooling action of the cooler on the recording medium based on information on a temperature of the recording medium.

A heating device is provided. The heating device includes a heating unit, heating a member to be heated, which is transported, and a contact portion of the heating unit contacting with the member to be heated; a heat pipe, having a first end and a second end opposite to the first end in a widthwise direction, and contacting with a portion of the heating unit different from the contact portion so as to extend in the widthwise direction crossing a transport direction of the member to be heated; a rotating body, rotating so as to press the member to be heated; and a power input unit, having a gear disposed on a second end side of the heat pipe and inputting a rotational force at least to the rotating body. The first end of the heat pipe has a thickness smaller than that of the second end.