An image forming apparatus includes an image forming device which forms an image on a recording medium and an image scanning device which transmits scanned image data to the image forming device. The image forming device includes a receiver, a first image forming unit, a second image forming unit, and a controller. The receiver receives at least one of external image data transmitted from an external device and the scanned image data as input image data. The first image forming unit forms a developer image based on the input image data on the recording medium. The second image forming unit forms a mark image on the recording medium. The controller determines whether to make the second image forming unit form the mark image or not depending on a type of a transmission source of the input image data.

An image forming apparatus to form image layers on a first recording medium and a second recording medium, and including a reception unit that receives a print job, a conveyance unit, an image forming unit, a re-conveyance unit, and a discharge unit. The conveyance unit sequentially conveys recording media to a recording position used to form an image layer on a recording medium. Each time a recording medium is conveyed to the recording position, the image forming unit forms one image layer on the conveyed recording medium based on the print job. The re-conveyance unit re-conveys the same recording media to the recording position. The second recording medium is conveyed to the recording position prior to the first recording medium unless the second recording medium and the first recording media are to receive the same number of image layers. Then, the first recording medium is conveyed to the recording position.

A charged positive toner having a positive polarity that attaches to a charge roller is moved from the charge roller to a photosensitive drum, and the positive toner is transferred to an intermediate transfer belt at a primary transfer portion at which a primary-transfer power supply forms an electric potential having a negative polarity. The primary-transfer power supply forms an electric potential having the positive polarity at the primary transfer portion, and the positive toner transferred to the intermediate transfer belt is moved together with the intermediate transfer belt and is collected by the charge roller in contact with a downstream photosensitive drum.

A charged positive toner having a positive polarity that attaches to a charge roller is moved from the charge roller to a photosensitive drum, and the positive toner is transferred to an intermediate transfer belt at a primary transfer portion at which a primary-transfer power supply forms an electric potential having a negative polarity. The primary-transfer power supply forms an electric potential having the positive polarity at the primary transfer portion, and the positive toner transferred to the intermediate transfer belt is moved together with the intermediate transfer belt and is collected by the charge roller in contact with a downstream photosensitive drum.

According to an embodiment, an image processing system includes an image forming unit, a decoloring unit, a storage device, an operation panel and a processor. The storage device stores image data of a plurality of printed materials. The processor forms on a sheet an image based on image data in a page range of the printed material received by the operation panel. The processor determines whether or not images of all pages in the page range have been decolored in a predetermined range after the image formation is executed when the formed image is decolored by the decoloring unit.

An image forming apparatus to form image layers on a first recording medium and a second recording medium, and including a reception unit that receives a print job, a conveyance unit, an image forming unit, a re-conveyance unit, and a discharge unit. The conveyance unit sequentially conveys recording media to a recording position used to form an image layer on a recording medium. Each time a recording medium is conveyed to the recording position, the image forming unit forms one image layer on the conveyed recording medium based on the print job. The re-conveyance unit re-conveys the same recording media to the recording position. The second recording medium is conveyed to the recording position prior to the first recording medium unless the second recording medium and the first recording media are to receive the same number of image layers. Then, the first recording medium is conveyed to the recording position.

An image forming apparatus includes a printer section and a controller. The printer section forms an image using a decolorable recording agent. The controller controls the printer section to form a concealing code image for concealing a secret code image indicating secret information which corresponds to a concealed object in an area at least a part of the secret code image with the decolorable recording agent in such a manner that the secret code image formed on the sheet cannot be decoded.

An image forming apparatus includes a printer section and a controller. The printer section forms an image using a decolorable recording agent. The controller controls the printer section to form a concealing code image for concealing a secret code image indicating secret information which corresponds to a concealed object in an area at least a part of the secret code image with the decolorable recording agent in such a manner that the secret code image formed on the sheet cannot be decoded.

A sheet discharging device includes a stacking portion configured to stack a sheet; a discharging portion configured to feed the sheet so as to be discharged to the stacking portion, wherein the discharging portion includes a first roller configured to feed the sheet and a second roller provided so as to be contactable to a sheet surface opposite from another sheet surface to which the first roller is contactable to; and an electrically discharging member configured to electrically discharge the sheet in contact with the sheet fed by the discharging portion. As viewed in a widthwise direction perpendicular to a discharging direction of the sheet, the electrically discharging member is provided so as to extend through between rotational axes of the first and second rollers in the discharging direction of the sheet.

A sheet discharging device includes a stacking portion configured to stack a sheet; a discharging portion configured to feed the sheet so as to be discharged to the stacking portion, wherein the discharging portion includes a first roller configured to feed the sheet and a second roller provided so as to be contactable to a sheet surface opposite from another sheet surface to which the first roller is contactable to; and an electrically discharging member configured to electrically discharge the sheet in contact with the sheet fed by the discharging portion. As viewed in a widthwise direction perpendicular to a discharging direction of the sheet, the electrically discharging member is provided so as to extend through between rotational axes of the first and second rollers in the discharging direction of the sheet.