A developing roller is capable of preventing the generation of a difference in image density between a central portion and an end portion of an electrographic image. The developing roller has an electro-conductive mandrel and an electro-conductive layer on the mandrel, the electro-conductive layer has a crown shape in which an outer diameter of a central portion in a direction along the mandrel is larger than outer diameters of both end portions in the direction along the mandrel, an outer surface of the developing roller includes a first region having an electrically insulating property and a second region having a higher conductive property than the first region, and the first region and the second region are disposed adjacent to each other.

A development device includes a housing, a development roller, and a layer thickness regulating blade, the layer thickness regulating blade including a support sheet metal and a blade rubber section, the blade rubber section including a contact portion and an extension, the contact portion contacting the development roller, the extension extending from the contact portion, the extension including a curved surface portion having a curved surface, the curved surface being formed to be closer to the support sheet metal in a thickness direction of the support sheet metal as being farther away from the contact portion, the curved surface having a curvature radius equal to or more than 1.5 mm and equal to or less than 3.0 mm, the curved surface portion having a height equal to or less than 1.0 mm in the thickness direction.

A developing roller is capable of preventing the generation of a difference in image density between a central portion and an end portion of an electrographic image. The developing roller has an electro-conductive mandrel and an electro-conductive layer on the mandrel, the electro-conductive layer has a crown shape in which an outer diameter of a central portion in a direction along the mandrel is larger than outer diameters of both end portions in the direction along the mandrel, an outer surface of the developing roller includes a first region having an electrically insulating property and a second region having a higher conductive property than the first region, and the first region and the second region are disposed adjacent to each other.

In an image forming apparatus, a conveyance section forms a conveyance path and conveys a sheet in a conveyance direction. The conveyance section includes a conveyance roller for rotating around a roller shaft extending in a direction orthogonal to the conveyance direction, and a guide member. The guide member includes a first guide member for rotating around a first axial line to open/close with respect to a first partial region of the conveyance path, and a second guide member for rotating around a second axial line to open/close with respect to a second partial region different from the first partial region. The first axial line extends in a direction parallel to a longitudinal direction of the roller shaft. The second axial line extends in a direction intersecting with the longitudinal direction. The first guide member opens in conjunction with an opening action of the second guide member.

The cleaning member is disposed to be opposite to the first roller with the second roller being provided therebetween. Compared to a case when the second roller is placed at a first position on a side of the first roller, if the second roller is placed at a second position on a side of the cleaning roller, a pressure between the second roller and the first roller becomes smaller, and a pressure between the second roller and the cleaning member becomes larger.

A rotation device includes: a first rotator that includes a recessed portion formed on an outer circumferential surface and that is rotatable in a predetermined rotation direction; a second rotator that comes into contact with a portion of the outer circumferential surface in a range from an upstream end to a downstream end of the recessed portion in the rotation direction and that is separated from the first rotator outward in a radial direction of the first rotator when the first rotator is in a position of rotation such that the recessed portion faces the second rotator; a first drive mechanism that rotates the first rotator or the second rotator and that causes the other of the first rotator or the second rotator to rotate in conjunction in a contact state in which the first rotator and the second rotator are in contact with each other; and a second drive mechanism that rotates the other in a separation state in which the first rotator and the second rotator are separated from each other.

To provide a roller device that can improve the life of a cleaning member and that enables a cleaning member to perform a cleaning operation even when a contact-pressure release operation is performed to release the contact-pressure of the second roller on the first roller and to provide a fixing device and an image forming apparatus.

The cleaning member is disposed to be opposite to the first roller with the second roller being provided therebetween. Compared to a case when the second roller is placed at a first position on a side of the first roller, if the second roller is placed at a second position on a side of the cleaning roller, a pressure between the second roller and the first roller becomes smaller, and a pressure between the second roller and the cleaning member becomes larger.

A paper feed roller of the present invention comprises a roller body 2 integrally formed of elastic material in a cylindrical shape in which a plurality of protruding lines 6 are disposed on a peripheral surface 5 at even intervals, wherein the roller body 2 is formed so that crest portions 6a and trough portions 6b are continuously provided in a circumferential direction, an opening angle is equal to or more than 2 and is equal to or less than 8, a radial height h of the protruding line is equal to or more than 0.051 mm and is equal to or less than 0.1 mm, and a curvature radius r1 at a shoulder is equal to or more than 0.55 mm.

A fixing device includes a first pressing member, a fixing belt, a second pressing member, a tensioning section on which the fixing belt is wound on an upstream side relative to the fixing nip in a rotation direction of the fixing belt and which is configured to impart tension to the fixing belt, and a control section configured to control the tensioning section such that the shape in an axial direction of the fixing belt is changed in accordance with a type of sheet which passes through the fixing nip.

A fixing device includes a first pressing member, a fixing belt, a second pressing member, a tensioning section on which the fixing belt is wound on an upstream side relative to the fixing nip in a rotation direction of the fixing belt and which is configured to impart tension to the fixing belt, and a control section configured to control the tensioning section such that the shape in an axial direction of the fixing belt is changed in accordance with a type of sheet which passes through the fixing nip.