A developing blade has a protrusion that protrudes toward a developing roller in an opposing portion facing the developing roller. When a height of the protrusion from an opposing surface that faces the developing roller at a position further toward a tip side than the protrusion is denoted by H (mm) and a length of the opposing surface extending toward the tip side perpendicular to an axial line direction of the developing roller is denoted by L (mm), when viewing a cross section perpendicular to a rotation axis of the developing roller, the following conditions are satisfied:

0.05≦H≦0.3, and

0.15≦L≦1.0.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference in density information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

An electrophotographic apparatus comprising an electrophotographic photosensitive member, a charging device and a developing device, wherein the charging device comprises a conductive member arranged to be capable of contacting the electrophotographic photosensitive member, the conductive layer at the outer surface of the conductive member comprises a matrix and a plurality of domains dispersed in the matrix, at least some of the domains are exposed at the outer surface of the conductive member, the matrix has a volume resistivity R1 of larger than 1.00×10.sup.12 Ω.Math.cm, the volume resistivity R1 of the matrix is 1.0×10.sup.5 times or more a volume resistivity R2 of the domains, the developing device comprises the toner comprising a toner particle and a silica fine particle, and a coverage ratio of the toner surface with the silica fine particles is from 62.0% by area to 100.0% by area as determined by X-ray photoelectron spectroscopy.

An image forming apparatus includes: a photosensitive drum; a developing roller; a separation mechanism for moving the developing roller between a contacting position contacting the photosensitive drum and a separated position separated from the photosensitive drum; a first tray; a first sheet feed mechanism for feeding a sheet from the first tray toward the photosensitive drum; a first sheet sensor for detecting passage of the sheet at a prescribed position; and a controller. The controller of the image forming apparatus is configured to perform: when a printing operation is performed onto the sheet ted from the first tray, feeding the sheet in the first tray to the prescribed position and maintain the sheet; moving, on or after the first sheet sensor detects the sheet, the developing roller to the contacting position.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference in density information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference in density information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

A charging device includes a charging member that is rotatable and contacts and electrically charges a surface of a charging target member; and a cleaning member that is rotatable and cleans a surface of the charging member, wherein the cleaning member includes a core bar extending in a lengthwise direction, a foam member that is helically wound around the core bar while forming a gap in the lengthwise direction and contacts the charging member, and a first adhesive agent that is provided between the foam member and the core bar, the first adhesive agent contacting a part of the foam member and another part of the foam member that are formed to adjoin each other in the lengthwise direction via the gap.

A charging device includes a charging member that is rotatable and contacts and electrically charges a surface of a charging target member; and a cleaning member that is rotatable and cleans a surface of the charging member, wherein the cleaning member includes a core bar extending in a lengthwise direction, a foam member that is helically wound around the core bar while forming a gap in the lengthwise direction and contacts the charging member, and a first adhesive agent that is provided between the foam member and the core bar, the first adhesive agent contacting a part of the foam member and another part of the foam member that are formed to adjoin each other in the lengthwise direction via the gap.

Disclosed is a developing device including a conveying screw and an inductance sensor. The inductance sensor includes a detector detecting magnetic permeability of the developer accommodated in a developing container and has such detection sensitivity that the detection sensitivity with which the detector detects magnetic permeability when a magnetic material is disposed at a position 1 mm away from the detector in a vertical direction is 10% or more of that when magnetic material is disposed at a position which is in contact with the detector. The conveying screw includes a rotary shaft; a blade which is spirally formed on an outer circumference of the rotary shaft; and a rib formed as to protrude outwardly from the outer circumference of the rotary shaft. The rib is disposed opposite the detector with respect to a conveying direction of the conveying screw. The rib is provided with a magnet.

A developing device includes a developing roller to rotate in a predetermined direction of rotation and opposed to or in contact with an image bearer to form a development range, a cover to cover the developing roller downstream from the development range in the predetermined direction of rotation, a sheet member cantilevered by the cover to contact the developing roller with a flat face of the sheet member while trailing along the predetermined direction of rotation at a position downstream from the development range. The cover includes a large gap portion to form a first gap in a first predetermined range in the predetermined direction of rotation and a small gap portion disposed adjacent to and downstream from the large gap portion in the predetermined direction of rotation to form a second gap smaller than the first gap in a second predetermined range in the predetermined direction of rotation.