In a case where a sheet jam detection unit detects that a sheet jam has occurred in an image bearing member, and determines that there is no sheet P at a nip portion, a printer control unit starts cleaning by a cleaning unit without waiting for removal of the sheet P causing the sheet jam.

In an image forming apparatus which includes a plurality of image forming units each including an image bearing member, a contact charging member, and a developer bearing member for forming toner of normal polarity, and which, in a printing operation, applies a charging bias having a first direction, in a cleaning operation, applies a charging bias having a second direction, and recovers residual toner remaining on the image bearing member which was not used for printing by the developer bearing member, before performing the cleaning operation, when successively performing the printing operation on a plurality of recording materials including a first recording material and a second recording material, which is used for printing following the first recording material, the charging voltage larger in absolute value in the printing operation for the second recording material than in the printing operation for the first recording material is applied.

A process cartridge includes a developer carrier including a dielectric portion and a conductive portion on a surface thereof, a regulation member, and an image carrier disposed so as to come into contact with the developer carrier. The developer carrier and the image carrier are rotationally driven such that a surface of the developer carrier and a surface of the image carrier move at linear velocities different from each other at a contact portion, and the developer remaining on the image carrier after the developer image is transferred from the image carrier, is collected by the developer carrier at the contact portion.

An image forming apparatus including a holding apparatus configured to collect residual developer remaining on an intermediate transfer belt and temporarily hold the residual developer, and a cleaning member configured to remove toner borne on the photosensitive drum that moves the toner held by the holding apparatus to the intermediate transfer belt and discharging the toner. Toner from a development roller is supplied to the cleaning member before toner reversely transferred from the intermediate transfer belt is supplied to the cleaning member.

An image forming apparatus includes plural image holding bodies that are provided for respective colors of toners and hold toner images having the respective colors, an intermediate transfer body onto which the toner images having the respective colors held by the plural image holding bodies are transferred, a waste toner collection unit that collects toners remaining on the intermediate transfer body as a waste toner in a case where the toner images having the respective colors transferred onto the intermediate transfer body are transferred onto a recording material, a waste toner developing unit that uses the waste toner collected by the waste toner collection unit to develop a toner image on an image holding body of the plural image holding bodies or the other image holding body of the plural image holding bodies, and a control unit that performs a control to cause the waste toner developing unit to develop the toner image in a case where a predetermined condition about a ratio of a waste toner having each color to the waste toner stored in the waste toner collection unit is satisfied.

An image forming apparatus includes a rotatable image bearing member, a developing member, a transfer member, and a brush contacting a surface of the image bearing member in a contact portion downstream of a transfer portion and upstream of a developing portion with respect to a rotational direction of the image bearing member. The toner which is not transferred onto a toner image receiving member is collected by the developing member. In a charging series, the toner is positioned on the same side as a normal charge polarity of the toner relative to the brush. In the contact portion, a maximum value of a contact pressure of 0.7 gf/mm.sup.2 or more and 3.5 gf/mm.sup.2 or less, a maximum contact area ratio is 18% or more and 74% or less, and a Clark-Evans index of the brush is 1 or more.

An image forming apparatus includes a charging unit that charges an image bearing member, a developing unit that forms a toner image on an latent image formed on the image bearing member, a transfer unit that transfers the toner image onto a transfer material, a charge neutralizer that neutralizes a charge of the image bearing member downstream of a transfer portion and upstream of a charging portion in a rotating direction of the image bearing member, a conductive collecting unit that collects a material adhering on the image bearing member downstream of the transfer portion and upstream of the charging portion, wherein the developing unit collects residual toner on the image bearing member, an voltage application unit sets a potential difference between the voltage applied to the collecting unit and the surface electric potential of the image bearing member not more than a discharge threshold.

An image forming apparatus capable of forming images in mono-color and a plurality of colors includes first and second image forming units and a control unit. The image forming unit includes a rotatable image bearing member, a rotatable developing member that contacts the image bearing member to supply a developer to the surface thereof, and a developer supply member that supplies the developer to the developing member. The control unit switches between an image forming operation of forming an image on the image bearing member surface and a cleaning operation of removing an attached matter on the image bearing member surface with the developing member by controlling a voltage applied to the developing member and a voltage applied to the developer supply member.

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 drum cleaner in a drum unit removes toner from a photosensitive drum. A waste-toner conveyance pipe has a waste-toner discharge port and conveys toner removed from the photosensitive drum by the drum cleaner. A toner accommodation chamber accommodates toner to be supplied to a developing roller. A waste-toner accommodation chamber accommodates toner removed from the photosensitive drum. A toner cartridge rotatably moves relative to the drum unit between: a first position at which a waste-toner receiving port is separated from the waste-toner discharge port in a state where the toner cartridge is mounted on the drum unit; and a second position at which an internal space of the waste-toner accommodation chamber is in communication with an internal space of the waste-toner conveyance pipe through the waste-toner discharge port and the waste-toner receiving port in a state where the toner cartridge is mounted on the drum unit.