An image forming device includes: a print engine to form an image on a medium, a sensor to irradiate light onto the medium and to detect an amount of light transmitted through the medium, and a processor to control the print engine based on the detected transmitted light amount and temperature data.

An image forming apparatus includes a latent image forming portion configured to form a latent image on an image bearing member; a developing device including a container configured to store toner and a developing member configured to supply the toner to the latent image formed on the image bearing member to form a toner image; an environment sensor configured to detect environmental information related to an environment in which the developing device is placed; and a controller configured to control switching between a first mode and a second mode, in which a number of prints per unit time is less than that in the first mode. The controller is configured to perform switching from the first mode to the second mode based on an update value obtained by adding or subtracting over time an index value weighted in accordance with the environmental information detected by the environment sensor.

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.

A control device of an image forming system including an image former that forms an image on a recording medium formed of a continuous sheet or a long sheet includes a hardware processor that calculates a width of the recording medium on a downstream side of a fixer included in the image former in a transport direction of the recording medium and outputs a shrinkage amount or a shrinkage rate of the recording medium in the transport direction due to the fixer based on the width of the recording medium and shrinkage characteristic information of the recording medium.

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 includes: sheet feeding trays; an image forming part that includes a fixing part and forms an image on a sheet fed from each of the sheet feeding trays based on a print job; and an acquisition part that acquires information indicating “presence” or “absence” of a possible carrier having a possibility of virus infection in a region where an apparatus main body is installed; and a hardware processor that is able to select an operation mode of the print job from a normal mode and a virus removal mode, and sets an operation mode of the print job to the virus removal mode, wherein in the virus removal mode, a fixing temperature of the fixing part is set to a predetermined temperature, and a heating time for the sheet in the fixing part is made longer than a heating time in the normal mode.

An image forming apparatus includes a controller configured to identify a selected sheet size setting as defined by a dimension in the width direction and a dimension in the conveyance direction, set a cooling threshold at a first threshold if the selected sheet size setting is a first size having a dimension in the width direction larger than a predetermined dimension, and a dimension in the conveyance direction larger than the dimension in the width direction, and set the cooling threshold at a second threshold lower than the first threshold if the selected sheet size setting is a second size having a dimension in the width direction that is the same as the dimension in the width direction of the first size, and a dimension in the conveyance direction smaller than the dimension in the width direction.

The image forming apparatus of the present embodiment has two limiters composed of a conventional high order limiter and a low order limiter, and carries out control to switch the limiter according to a temperature and a humidity so as not to reach a image contrast potential equal to or greater than those limiters. Carrier development can occur if image formation is performed in a state where the image contrast potential is high. Therefore, by providing a low order limiter as in the present embodiment and carrying out control so as not to exceed the low order limiter at the time of the image formation, an occurrence of the carrier development can be suppressed, and an image density can also be within a prescribed range.

An image forming apparatus analyzes image data received by a receiving unit, determines whether or not there is a toner applied region in which an amount of toner to be transferred to a sheet is larger than the first threshold and smaller than the second threshold, sets the fixing temperature of a fixing unit to the first temperature when it is determined that there is not the toner applied region, and sets the fixing temperature of the fixing unit to the second temperature higher than the first temperature when it is determined that there is the toner applied region and an ambient state sensed by an environment sensor indicates a high-humidity environment.

An image forming apparatus includes a transfer unit that transfers a toner image on an image bearer onto a transfer medium. The image forming apparatus includes a control unit that controls a transfer voltage to be output to the transfer unit in accordance with a certain condition. The control unit applies currents having at least two different values while paper is not being fed. The two current values are lower than a current value during paper feeding. The control unit estimates an output voltage on a basis of a voltage detected through the application of the currents. When the estimated output voltage falls below a certain limiter voltage, the control unit controls to bring the output voltage to a value calculated through the certain condition. When the estimated output voltage exceeds the certain limiter voltage, the control unit controls to bring the output voltage to the limiter voltage.