In a configuration in which a voltage of polarity opposite to charging polarity of toner is applied to a conveyance guide, controlling deposition of toner on the conveyance guide has been difficult. When performing duplex image formation, a potential difference between a surface potential of a photoconductive drum charged by a charging roller and a potential of the conveyance guide is smaller during printing on the second surface than during printing on the first surface.

Even from a plurality of small documents, their front-side and back-side images to be formed on a recording paper sheet, with alignment and coincidence of the front-side and back-side images of each document between the front and back sides of the recording paper sheet. In an image forming apparatus, an image processing section detects a front-side image of an original document from a scan area read in a first scan by an image reading section, detects a back-side image of the original document from a scan area read in a second scan, and moves or rotates the front-side image and the back-side image of the original document in terms of a whole image of the scan area so that the front-side image and the back-side image of the original document are brought into alignment and coincidence between a front side and a back side of a recording paper sheet.

An image forming apparatus including an image forming portion, a moving portion, a re-conveyance portion, a detection portion, and a control portion is provided. The image forming portion is configured to form an image on a sheet that is conveyed. The moving portion is configured to move the sheet in a width direction. The re-conveyance portion is configured to invert the sheet having the image formed on a first surface thereof convey the sheet to the image forming portion again. The control portion is configured to control, based on a detection result of the detection portion, the moving portion to move the sheet in the width direction such that the center of the image formed on the first surface in the width direction and a center of the image to be formed on the second surface in the width direction coincide.

An image forming apparatus includes an image forming portion, a transfer portion, an adjustment portion, a detection portion, a reverse and re-conveyance portion, and a controller configured to determine a second image position, on the image bearing member, of an image to be transferred onto a second surface of the sheet re-conveyed by the reverse and re-conveyance portion based on a side edge position, detected by the detection portion, of a trailing part of the sheet being conveyed with the first end as the leading edge, the controller being also configured to determine a shift amount by which the adjustment portion shifts the sheet re-conveyed by the reverse and re-conveyance portion based on the second image position and a side edge position, detected by the detection portion, of the sheet, which has been re-conveyed by the reverse and re-conveyance portion, being conveyed with the second end as the leading edge.

An image forming apparatus suppresses the occurrence of dew condensation in a post-processing operation when the sheet is jammed. When information indicating that a sheet is jammed is received, if the sheet detecting sensor detects the sheet on a switching member, a controller executes a conveying action to drive the sheet conveying portion until an upstream edge of the sheet in the sheet conveyance direction passes through the switching member and then stops the sheet conveying portion.

An image forming apparatus includes an image forming portion, an oblique movement correcting portion including a first registration roller pair and a first moving portion, a reversing portion, and a re-feeding portion. The reversing portion includes a reversing roller pair and a second moving portion. The re-feeding portion includes a second registration roller pair. When an image is formed on a second surface of a sheet opposite from a first surface of the sheet, a side end position of the sheet is corrected by the second moving portion and oblique movement of the sheet is corrected, and then the side end position of the sheet is corrected again by the first moving means and the sheet is fed to the image forming portion.

An example image forming apparatus includes, a main body, a first fixing device disposed in the main body to primarily fix a toner image transferred on a printing medium while passing through a transfer device, a first discharge device to discharge the printing medium having passed through the first fixing device from the main body, and a second fixing device disposed in the main body to additionally fix the toner image on the printing medium having passed through the first fixing device, wherein the second fixing device may be supplied with the printing medium through a connection path returning from the first discharge device into the main body and connected to the second fixing device.

A sheet conveyance apparatus includes a first conveyance portion configured to convey a sheet, a second conveyance portion configured to convey the sheet, the second conveyance portion including an abutment portion configured to form a loop on the sheet by being abutted against a leading edge of a sheet conveyed by the first conveyance portion, a curved guide portion, which is curved, configured to guide the sheet conveyed by the first conveyance portion to the second conveyance portion, and a rotary member arranged downstream of the first conveyance portion and upstream of the second conveyance portion in a sheet conveyance direction, and configured to be driven to rotate by a surface of the sheet that is guided by the curved guide portion, the surface sliding against the curved guide portion.

An image forming apparatus includes an image forming portion, an oblique movement correcting portion including a first registration roller pair and a first moving portion, a reversing portion, and a re-feeding portion. The reversing portion includes a reversing roller pair and a second moving portion. The re-feeding portion includes a second registration roller pair. When an image is formed on a second surface of a sheet opposite from a first surface of the sheet, a side end position of the sheet is corrected by the second moving portion and oblique movement of the sheet is corrected, and then the side end position of the sheet is corrected again by the first moving means and the sheet is fed to the image forming portion.

An image forming apparatus includes an image forming unit, a fixing unit including a first rotary member and a second rotary member, a reciprocation mechanism configured to reciprocally move the fixing unit in a width direction, a duplex conveyance unit configured to reverse a recording material of which a toner image is fixed on a first surface and reconvey the recording material to the image forming unit in a double-sided image formation in which toner images are formed and fixed on the first surface and second surfaces of the recording material, and a control unit configured to control the reciprocation mechanism not to move the fixing unit in the width direction while the fixing unit is nipping and conveying the recording material at a fixing nip portion for fixing the toner image on the first surface of the recording material in the double-sided image formation.