An image forming apparatus including an image bearing member, a charging member, a developing roller, a transfer roller, and a brush configured to be brought into contact with a surface of the image bearing member on a side downstream of a transfer portion and upstream of a charging portion in a rotation direction of the image bearing member and in which, wherein, after the transfer of a developer image onto a transferred member, a developer remaining on the surface of the image bearing member is collected by the developing roller, the brush is disposed such that, in a cross section perpendicular to a rotation axis of the image bearing member, a contact region of the surface of the image bearing member in contact with the brush overlaps a virtual line containing the rotation axis of the image bearing member and extending upward from the rotation axis in a vertical direction.

Provided is an inexpensive image forming apparatus capable of monitoring the generating state of various powders. The image forming apparatus includes a minute-particle-measuring device, a toner-particles-detecting air duct, a paper dust-detecting air duct, and blower fans. The minute-particle-measuring device detects the concentration of minute particles in air. The toner-particle-detecting air duct is an air duct leading from the image forming unit to the minute-particle-measuring device. The paper-dust-detecting air duct is an air duct leading from the paper-conveying path to the minute-particle-measuring device. The blower fans are respectively provided in the toner-particle-detecting air duct and the paper-dust-detecting air duct, and generate airflow that flows toward the minute-particle-measuring device side. The blower fans in the toner-particle-detecting air duct and in the paper-dust-detecting air duct are switched.

An image forming apparatus includes a paper dust collecting unit which collects, by application of a voltage, paper dust attached to a sheet, an optical detection unit provided on a downstream side of the paper dust collecting unit in a sheet conveyance direction, which irradiates the sheet with light and receives light via the sheet, a guide member which comes into contact with the sheet to be conveyed to guide the sheet, at least one of light directed toward the sheet from the optical detection unit and light directed toward the optical detection unit from the sheet passing through the guide member, and a control unit which switches a polarity of the voltage to be applied to the paper dust collecting unit and causes the sheet charged through the paper dust collecting unit to be conveyed to the guide member.

An image forming apparatus includes a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a brush, a voltage applying portion, and a control portion controlling a surface potential of the photosensitive member at the brush contacting position. When a value of subtracting a value of the surface potential of the photosensitive member in the brush contacting position from a value of the brush voltage is defined as a contacting position potential difference, the control portion controls the surface potential of the photosensitive member in the brush contacting position so that the contacting position potential difference is changed from a first potential difference to a second potential difference in a predetermined direction which is either one of an increasing direction or a decreasing direction, and then the contacting position potential difference is changed from the second potential difference to a third potential difference in the predetermined direction.

An image forming apparatus including an image bearing member, a charging member, a developing roller, a transfer roller, and a brush configured to be brought into contact with a surface of the image bearing member on a side downstream of a transfer portion and upstream of a charging portion in a rotation direction of the image bearing member and in which, wherein, after the transfer of a developer image onto a transferred member, a developer remaining on the surface of the image bearing member is collected by the developing roller, the brush is disposed such that, in a cross section perpendicular to a rotation axis of the image bearing member, a contact region of the surface of the image bearing member in contact with the brush overlaps a virtual line containing the rotation axis of the image bearing member and extending upward from the rotation axis in a vertical direction.

An image forming apparatus includes a photosensitive drum, a development roller configured to supply developer to the photosensitive drum, a transfer roller configured to transfer a developer image formed on the photosensitive drum to a recording material, and a cleaning roller being in contact with the photosensitive drum, configured to clean a part of the recording material adhered to the photosensitive drum, wherein the diameter of the transfer roller is greater than the diameter of the development roller and the diameter of the cleaning roller is greater than the diameter of the development roller.

An image forming apparatus includes a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a brush, a voltage applying portion, and a control portion controlling a surface potential of the photosensitive member at the brush contacting position. When a value of subtracting a value of the surface potential of the photosensitive member in the brush contacting position from a value of the brush voltage is defined as a contacting position potential difference, the control portion controls the surface potential of the photosensitive member in the brush contacting position so that the contacting position potential difference is changed from a first potential difference to a second potential difference in a predetermined direction which is either one of an increasing direction or a decreasing direction, and then the contacting position potential difference is changed from the second potential difference to a third potential difference in the predetermined direction.

An electrostatic collecting device includes a rotatable collecting body including a collecting member for forming a collecting portion in contact with an object-to-be-cleaned and formed of an insulator, wherein the rotatable collecting body rubs the object-to-be-cleaned in the collecting portion with the collecting member by rotation thereof, and collects, in the collecting member, a substance-to-be-collected from the object-to-be-cleaned moved relative to the collecting portion; a removing member for removing the substance-to-be-collected from the collecting member; and a charge-removing member provided opposed to the object-to-be-cleaned on a side downstream of the collecting portion with respect to a movement direction of the object-to-be-cleaned relative to the collecting portion. The charge-removing member constitutes at least a part of at least one of the rotatable collecting body and the removing member. The charge-removing member is electrically connected to an electric conductor which is in non-contact with the object-to-be-cleaned.

An image forming apparatus includes a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a brush, a voltage applying portion, and a control portion controlling a surface potential of the photosensitive member at the brush contacting position. When a value of subtracting a value of the surface potential of the photosensitive member in the brush contacting position from a value of the brush voltage is defined as a contacting position potential difference, the control portion controls the surface potential of the photosensitive member in the brush contacting position so that the contacting position potential difference is changed from a first potential difference to a second potential difference in a predetermined direction which is either one of an increasing direction or a decreasing direction, and then the contacting position potential difference is changed from the second potential difference to a third potential difference in the predetermined direction.

An image forming apparatus includes a photoconductor; a charging device to charge a first surface of the photoconductor; and a developing device including a developing roller to: rotate in one direction while contacting the first surface of the photoconductor; and develop a latent image of toner on the first surface of the photoconductor; and collect the toner adhered to the first surface of the photoconductor; and a supply roller to: rotate in the one direction while contacting a second surface of the developing roller; supply the toner in the developing device to the second surface of the developing roller; and collect foreign matter adhered to the second surface of the developing roller, the foreign matter moved from the first surface of the photoconductor to the second surface of the developing roller.