In a feeding direction of a recording material, a recording material cooling device is provided downstream of a fixing device, a curl reducing device is provided downstream of the recording material cooling device, and another recording material cooling device is provided downstream of the curl reducing device. By this configuration, occurrence of image defect by the recording material cooling device during the feeding of the recording material can be suppressed, and the curling of the recording material can be reduced after the recording material is cooled.

An image forming apparatus includes an image forming device; a fixing device; a first conveyance passage downstream from the fixing device in a sheet conveyance direction; a second conveyance passage downstream from the fixing device and communicating with the first conveyance passage; a sheet reversing member to reverse a conveyance direction of the sheet to the second conveyance passage; a divider to switch a route of the sheet between the first conveyance passage and the second conveyance passage; and a sheet detection sensor disposed downstream from the fixing device and upstream from the divider. The first conveyance passage includes a sheet outlet from which the sheet is ejected outside the apparatus. The apparatus further includes a ventilation passage communicating with an outside, to guide air from the outside to pass the sheet detection sensor and enter at least one of the first conveyance passage and the second conveyance passage.

An image forming apparatus includes an image bearing member configured to bear a non-fixed toner image, a transfer portion configured to transfer the non-fixed toner image onto a sheet at a transfer nip, a fixing portion including a first rotary member, a second rotary member and a heating portion configured to heat the first rotary member, a control portion configured to execute a nip image forming process of forming a nip image, on the sheet, corresponding to a shape of the fixing nip, and a reading unit configured to read the nip image, wherein the control portion sets the heating portion to a first temperature in a case where the non-fixed toner image passes through the fixing nip and sets the heating portion to a second temperature which is lower than the first temperature in a case where the nip image passes through the fixing nip.

A static elimination device includes: a discharge electrode that is arranged in a non-contact state with respect to a medium and eliminates static from the medium; and a power source that applies a discharge voltage including at least an alternating-current component to the discharge electrode, in which

f/v0.8(expression 1) is satisfied, where the transport speed of the medium is v (mm/sec.) and the frequency of the discharge electrode is f (Hz).

A static elimination device includes: a first static elimination member that makes contact with a medium that is transported; a second static elimination member arranged such that the medium is inserted between the first static elimination member and the second static elimination member; and a power source that applies a voltage to at least one of the first static elimination member or the second static elimination member, in which at least one of the first static elimination member and the second static elimination member has an elastic body.

The number of circulatable sheets and the conveying speed of a sheet are decided by referring to a storage unit which stores the number of circulatable sheets and the conveying speed of a sheet in correspondence with the type and size of a sheet, and the resolution of an image to be printed. It is determined whether the conveying speed of the feed surface of a sheet to be fed next to the printing unit and that of a feed surface to be refed next to the printing unit coincide with each other. It is determined whether the conveying speed of the feed surface of the sheet to be fed next to the printing unit and that of the feed surface or the refeed surface of a sheet immediately previously fed to the printing unit differ from each other.

A duplex printing method includes, determining an amount of shrinkage of a media sheet onto which a front side image has been printed; scaling an image to be printed on a back side of the sheet with a scaling function that depends upon the determined shrinkage; and printing the scaled image on the back side of the sheet. The step of determining includes predicting a shrinkage of a media sheet on the basis of process parameters, and on the basis of a model that is defined by a set of model parameters and that describes a dependence of the shrinkage on the process parameters, the process parameters including at least an amount of marking material to be applied to the front side of the sheet; measuring an actual shrinkage of the sheet; and adjusting the model parameters based on a comparison between the predicted shrinkage and the measured shrinkage to improve a prediction of a shrinkage for a subsequent sheet.

An image forming apparatus includes a conveying device, an image forming device, a reading device, and control circuitry. The conveying device sequentially conveys a plurality of successive recording media that includes a preceding recording medium and a following recording medium. The image forming device forms an image on each of a front surface and a back surface of the preceding recording medium conveyed. The reading device reads an outer shape of the preceding recording medium. The control circuitry calculates an amount of deformation of the preceding recording medium based on the outer shape of the preceding recording medium read. The control circuitry corrects at least one of a front image and a back image based on the amount of deformation calculated, to cause the image forming device to form the front image and the back image on a front surface and a back surface, respectively, of the following recording medium.

In a feeding direction of a recording material S, a recording material cooling device 20 is provided downstream of a fixing device 11, the curl reducing device 700 is provided downstream of the recording material cooling device 20, and a recording material cooling device 201 is provided downstream of the curl reducing device 700. By this, occurrence of image defect by the recording material cooling device 20 during the feeding of the recording material S can be suppressed, and the curling of the recording material can be reduced after the recording material S is cooled.

An image forming apparatus includes an engine to form an image on an image forming medium, a paper transfer device to pick up a printing paper and transfer the paper to a transfer path, a sensor to sense a printing paper at a predetermined position on the transfer path, and a processor to determine whether a transfer delay occurs, when the printing paper is sensed, and adjust a pickup timing to advance a pickup of a printing paper of a next page.