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.

A sheet conveyance apparatus includes a conveyance portion including a rotary member, and a counter member, a first contact member, a second contact member, and a contacting and separating mechanism. The contacting and separating mechanism causes the second contact member to separate from the surface of a rotary member of a conveyance portion when the rotary member rotates in the first direction, and causes the second contact member to abut against the surface of the rotary member when the rotary member rotates in a second direction opposite to the first direction.

A cleaning brush is provided. A cleaning unit comprises cleaning beans fixed on a surface of the carrier in a bi-spiral arrangement. The cleaning beans are arranged in an unequally-spaced manner on center of the carrier along a baseline; and, thus, bi-spirals are formed on the center and coiled in two different outward directions. Two annular spiral curve paths are formed with the cleaning beans as coiling the carrier and extending along the two directions. When the carrier cleans an electronic device, a solution or cleaning agent is discharged along the curve paths in spiral tangential directions. Hence, the bi-spiral cleaning unit obtains positive and negative directions on rotating to create a plurality of flow fields. Dirt is discharged easily with water distribution enhanced as compared to unidirectional spiral cleaning devices while a large contact surface, a good cleaning efficiency, and a high decontamination ratio are achieved.

The undercoat layer contains metal particles and a polyamide resin. The metal particle has a core and a coat layer covering at least a part of the core. The core contains titanium oxide. The coat layer contains at least a metal oxide different from titanium oxide. The metal oxide different from the titanium oxide is located on the outermost surface of the metal particles. The polyamide resin has an amide bond and an alkylene group. The absorption rate of the first peak derived from the amide bond to the second peak derived from the alkylene group to the first absorbance measured by infrared spectroscopy is ≥0.70.

A foreign substance collection apparatus includes: a frame body; a photosensitive drum; a cleaning roller which collects foreign substances from a surface of the photosensitive drum; a collecting roller which further collects the foreign substances having been collected by the cleaning roller from the cleaning roller; and a scraping member which scrapes off the foreign substances from the collecting roller. A foreign substance collecting portion included in the frame body has, in a posture during use: a first inner bottom surface which is positioned below the scraping member in a gravity direction; an outer bottom surface which is positioned further below the first inner bottom surface; and a connecting surface which intersects the first inner bottom surface and the outer bottom surface and which connects the first inner bottom surface and the outer bottom surface with each other.

A rotary-body support structure includes: a rotary body including a rotary shaft and a contact portion spirally wound around the rotary shaft; and bearing parts that rotatably support the rotary body. The amount of engagement of the rotary body with a contact body that is in contact with the contact portion of the rotary body changes when the rotary body moves toward one side in a rotation axis direction.

An image forming unit forms a toner image on an image carrier using toner. A transfer unit transfers the toner image to a sheet. A cleaner removes, from the image carrier, residual toner that was not transferred to the sheet by the transfer unit. In a detection mode for detecting a part of the image forming apparatus causing a streak, a controller may control the image forming unit to form a pattern on the image carrier, control the transfer unit so that the pattern passes through a transfer position without transferring the pattern to the sheet, control the cleaner to remove the pattern on the image carrier, and control the transfer unit to transfer a residual streak from the image carrier to the sheet. The residual streak occurs from the pattern image by causing an error of the cleaner.

A drum cartridge is mountable in and dismountable from an image forming apparatus without including a developing device. The drum cartridge includes an image bearing member, a charging member, and a cleaning member. The cleaning member includes an elastic layer contacting the charging member. The elastic layer includes a foam member and is made of a material having Asker-C hardness of 5-30 degrees.

A charging device includes a charging roller, a cleaning roller, a pair of first supporting members, a pair of second supporting members and a pair of elastic members. The pair of first supporting members supports the charging roller in a rotatable manner. The pair of second supporting members supports the cleaning roller in a rotatable manner. The pair of elastic members is disposed between the first supporting members and the second supporting members, and pushes back the cleaning roller in a direction separate away from the charging roller. The second supporting member provided on one side in an axial direction of the cleaning roller has a roller-shift preventing part which blocks the cleaning roller. The elastic member provided on the one side in the axial direction pushes back the cleaning roller with force smaller than force of the elastic member provided on the other side in the axial direction.

A cleaning brush is provided. A cleaning unit comprises cleaning beans fixed on a surface of the carrier in a bi-spiral arrangement. The cleaning beans are arranged in an unequally-spaced manner on center of the carrier along a baseline; and, thus, bi-spirals are formed on the center and coiled in two different outward directions. Two annular spiral curve paths are formed with the cleaning beans as coiling the carrier and extending along the two directions. When the carrier cleans an electronic device, a solution or cleaning agent is discharged along the curve paths in spiral tangential directions. Hence, the bi-spiral cleaning unit obtains positive and negative directions on rotating to create a plurality of flow fields. Dirt is discharged easily with water distribution enhanced as compared to unidirectional spiral cleaning devices while a large contact surface, a good cleaning efficiency, and a high decontamination ratio are achieved.