Selecting one conveyance mode from a plurality of conveyance modes includes a first selection process of selecting the one conveyance mode based on a detection temperature of a temperature sensor from a first time point at which rotation of a fixing rotator is started to a second time point at which a particular period elapses from the first time point. The first selection process includes: determining whether an initial temperature is higher than or equal to a first temperature, the initial temperature being a detection temperature of the temperature sensor when a print instruction is received; in response to determining that the initial temperature is lower than the first temperature, setting the particular period to a first period; and in response to determining that the initial temperature is higher than or equal to the first temperature, setting the particular period to a second period longer than the first period.

There is used an image forming apparatus including a fixing unit configured to heat a recording material at a fixing nip portion to fix a toner image, and a control unit configured to switch a target temperature, wherein, in the case where the target temperature of preceding recording material is first temperature, the target temperature of subsequent recording material is second temperature which is higher than the first temperature, and a difference between the second temperature and the first temperature has a first value, the control unit performs switching from timing which is earlier than reaching of the second recording material to the fixing nip portion by a predetermined period, and, the higher the target temperature of the preceding recording material, the shorter the predetermined period.

Printing apparatuses include a photoreceptor adapted to print an image by applying marking material to print media, a fuser adapted to heat the marking material on the print media, and a controller. The controller determines the amount of marking material per unit area of the image before the fuser heats the marking material on the print media. The controller rasterizes the image to produce a bitmap of the image, but the amount of marking material per unit area for the image is determined before completion of rasterization and marking of the image. The controller also adjusts the operating temperature of the fuser to a fusing temperature based on the amount of marking material per unit area of the image, causes the photoreceptor to print the image on the print media using the bitmap of the image, and causes the fuser to fuse the marking material to the print media.

A fixing device includes a fixing belt, a pressing roller and a heating part. The heating part includes a heater, a plurality of temperature sensors, a heater holding member and a sensor holding member. The sensor holding member holds the temperature sensors between the heater holding member and the sensor holding member. The heater holding member has observation holes through which the heater is exposed. The heater holding member has a guide part which positions the sensor holding member with respect to the heater holding member. The sensor holding member has an engagement part engaged with the guide part. The sensor holding member holds each of the temperature sensors at a position corresponding to each of the observation holes by engagement of the engagement part with the guide part.

Power to an electrical device is controlled using a phase control that changes a cutoff phase of an alternating current (AC) electrical signal delivered to the electrical device. The power delivered to the electrical device is increased to an operational level using the phase control. A level of the power delivered to the electrical device is maintained at the operational level using an integral half cycle control that selectively removes a plurality of half cycles from the AC electrical signal delivered to the electrical device such that a plurality of remaining half cycles in the AC electrical signal delivered to the electrical device have a frequency outside a range of sub-harmonic frequencies.

An image forming apparatus is configured to execute image forming processing of forming an image on a sheet. The apparatus includes a photosensitive drum, a fixing device including a heater and a roller, a main motor configured to generate a driving force, a driving mechanism having a connected state in which the driving force is transmittable to both the roller and the photosensitive drum, and a disconnected state in which the driving force is transmittable to the roller but is not transmitted to the photosensitive drum, a temperature sensor configured to detect a temperature of the fixing device, and a controller. In a case where the image forming processing is started, the controller sets the driving mechanism into the disconnected state, rotates the main motor at a preheating speed, and executes preheating processing in which the fixing device is heated by the heater.

An image forming apparatus comprises a main body casing; a fixing unit which fixes a developer to a sheet by means of heating and pressurization; a fan which is provided to discharge air inside the main body casing to outside of the main body casing; and a controller. The fixing unit includes a heating unit which heats the sheet; and a temperature sensor which detects a temperature of the heating unit. When the fixing unit is fixing the developer to the sheet, the controller is configured to: determine a heating unit temperature based on the temperature detected by the temperature sensor; stop the fan in a case of determining that the heating unit temperature is not less than a threshold value; and drive the fan in a case of determining that the heating unit temperature is less than the threshold value.

There is provided image forming apparatus including: casing; temperature sensor configured to detect temperature in the casing; image forming unit configured to form toner image on sheet; fuser which has heating member configured to heat the sheet, and which is configured to fix the toner image to the sheet; a fan; and a controller. The controller is configured to execute: changing of driving speed of the fan; and waiting control including: stopping supply, to the image forming unit, of next sheet, before the changing of the driving speed; completing the fixing of the toner image to the sheet, before the changing of the driving speed; and restarting supply of the next sheet to the image forming unit after the changing of the driving speed and after waiting time has elapsed since the completion of the fixing of the toner image to the sheet.

A fixing device (50) includes a fixing belt (70), a pressure member (80), and a heating section (90). The heating section (90) faces an inner peripheral surface of the fixing belt (70). The heating section (90) includes a heater (HT), a first heat sensitive body (SM11), and a second heat sensitive body (SM21). The second heat sensitive body (SM21) differs from the first heat sensitive body (SM11). The heater (HT) has a first heater portion (AE1). The first heater portion (AE1) is one end portion of a pair of end portions of the heater (HT) in a longitudinal direction thereof. The first heat sensitive body (SM11) and the second heat sensitive body (SM21) face the first heater portion (AE1) and are aligned in a conveyance direction (DC) of a sheet (S).

An image forming apparatus includes a fixing member, a heating portion configured to heat the fixing member by being supplied with electric power, a power source configured to supply electric power to the heating portion, a temperature detector, a controller configured to control power supply from the power source to the heating portion based on the output voltage from the temperature detector, a reference voltage generator configured to generate a reference voltage, and a breaker configured to stop the power supply from the power source to the heating portion. The reference voltage generator is configured to output the reference voltage that changes with time having elapsed since a start of heating at which the power supply to the heating portion was started by the controller.